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Organ Bath (organ + bath)
Selected AbstractsSpasmogenic action of endothelin-1 on isolated equine pulmonary artery and bronchusEQUINE VETERINARY JOURNAL, Issue 2 2003A. E. M. BENAMOU Summary Reasons for performing study: There is currently little published information about the effects of endothelin-1 (ET-1), a potent endogenous spasmogen of vascular and airway smooth muscle, on pulmonary vasculature and airways or which ET receptor subtypes mediate ET-1-induced vasoconstrictive and bronchoconstrictive action in the horse. Objectives: To investigate the effect of endothelin-1 (ET-1) on smooth muscle from isolated equine pulmonary artery and bronchus. In addition, the roles of ETA and ETB receptors in ET-1 mediated contraction in these tissues were assessed. Methods: The force generation of ring segments from pulmonary arteries or third-generation airways (obtained from horses subjected to euthanasia fororthopaedic reasons) were studied in an organ bath at 37°C in response to exogenous endothelin and selective endothelin A (BQ123) or B receptor (BQ788) antagonists. Results: ET-1 produced concentration-dependent contractions of the equine pulmonary artery and bronchus. The threshold for contraction was 10,10 and 10,9 mol/l ET-1 for pulmonary artery and bronchus, respectively. The maximal contraction induced by the highest ET-1 concentration (10,7 mol/l) was 173 and 194% of the contraction obtained with 100 mmol/l KCl in pulmonary artery and bronchus, respectively. ET-1 potency was 25 times greater in equine pulmonary artery than in equine bronchus (concentration of ET-1 producing 50% of maximal contraction [EC50] = 5.6 10,9 mol/l and 2.2 10,8 mol/l, respectively). In pulmonary artery, ET-1 induced contractions were significantly inhibited by the ETA receptor antagonist BQ123 (1 ,mol/l; dose-response curve to ET-1 was shifted to the right by 5.4-fold), but not by the ETB antagonist BQ788. In bronchus, dose-responses curves to ET-1 were shifted to the right by BQ123 (1 ,mol/l; 2.5-fold), but not by BQ788 (1 ,mol/l). In the presence of both antagonists, the dose-response curve to ET-1 was shifted to the right by 4.5-fold. Conclusions: These functional studies demonstrate that ET-1 is a potent spasmogen of equine third generation pulmonary artery and bronchus, and that contractions are mediated via ETA receptors in the former and both ETA and ETB receptors in the latter. Potential clinical relevance: Endothelin receptor antagonists may have potential for treating equine pulmonary hypertension or bronchoconstriction. [source] Abstract no.: 2 The influence of clozapine on tone of isolated bovine retinal arteriesFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005Koen Boussery Aims:, It has been suggested that the atypical antipsychotic drug clozapine might be helpful in the development of new antiglaucoma agents, since it combines lowering of the intra-ocular pressure after topical instillation with vasodilation. However, the vasoactive influence of clozapine on ocular blood vessels has never been analysed. Therefore, this study aimed to evaluate whether clozapine has direct vasodilatory effects in isolated bovine retinal arteries (BRA) and to characterise pharmacologically the mechanisms involved. Methods:, Retinal arteries were isolated from bovine eyes and mounted in a wire-myograph for isometric tension recording. Concentration-response curves were generated by cumulative addition of clozapine (1 nM to 10 ,M) to the organ bath. Results:, Clozapine elicited a concentration-dependent relaxation of the BRA. Removal of the endothelium of the BRA, inhibition of nitric oxide synthase with N, -nitro-L-arginine and inhibition of soluble guanylyl cyclase with ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) significantly attenuated the clozapine-response, whereas cyclo-oxygenase inhibition with indomethacin had no influence. The Ca2+ channel activator Bay k8644, the nonselective 5-hydroxytryptamine receptor antagonist methiothepin and the adenosine receptor antagonist 8-(p-sulfophenyl) theophylline also failed in affecting the clozapine-induced relaxations. Conclusion:, Clozapine clearly relaxes bovine retinal arteries in a direct way. Endothelium-derived NO is involved in this response. However, prostanoids, calcium entry blockade, 5-HT7 receptor stimulation and adenosine receptor stimulation all seem to be not involved. [source] Effect of exogenous glutamate and N-Methyl-D-aspartic acid on spontaneous activity of isolated human ureterINTERNATIONAL JOURNAL OF UROLOGY, Issue 9 2007Slobodan M Jankovic Objectives: While the neurotransmitter role of glutamate in the gastrointestinal tract has been shown, its effects on smooth muscle of the human ureter have not previously been investigated. In our study we have investigated the effects of exogenous glutamate on the spontaneous activity of isolated human ureter, taken from 14 adult patients after nephrectomy. Methods: The segment of ureter, excised 3 cm distal from the pyeloureteral junction, was isolated in an organ bath. Both longitudinal tension and intraluminal pressure of the segment were recorded simultaneously. Results: Glutamate administered in the lumen of the isolated ureteral segments (7.8 × 10,7 M/L,3.5 × 10,2 M/L) was ineffective. When added to the isolated organ bath from the serous side of the ureteral segment, glutamate (7.9 × 10,6 M/L,10.6 × 10,3 M/L) and N-Methyl-D-aspartic acid (NMDA) (9.1 × 10,8 M/L,3.1 × 10,5 M/L) produced a concentration-dependent increase in spontaneous activity of the isolated preparations, while kainic acid (6.3 × 10,8 M/L,10.5 × 10,5 M/L) and (+/,)- trans -1-Aminocyclopentane- trans -1,3-dicarboxylic acid (ACPD) (7.7 × 10,8 M/L ,6.5 × 10,5 M/L) were ineffective. Conclusions: The results of our study suggest that an excitatory neurotransmitter glutamate stimulates spontaneous activity of the human ureter through activation of NMDA ionotropic receptors, located on smooth muscle cells or intramural nerve fibers [source] The neuronal and endothelium-dependent relaxing responses of human corpus cavernosum under physiological oxygen tension last longer than previously expectedINTERNATIONAL JOURNAL OF UROLOGY, Issue 5 2004KAZUNORI KIMURA Abstract Background: Intracavernosal oxygen tension varies greatly in the process of erection. Blood extracted from the human penis demonstrates an increase from approximately 30 mmHg Po2 in the flaccid state to 100 mmHg in the erect state of the penis. In the present study, using these levels as a guide, we investigate how the NO-dependent relaxation of human corpus cavernosum changed under physiological oxygen tensions ranging from approximately 30 to 100 mmHg. Methods: Human penile tissue specimens were obtained at penile surgery with informed consent from the patients. The preparations were mounted in Krebs solution in an organ bath and the isometric tension was recorded. Krebs solutions of various oxygen tensions were prepared by bubbling 5% CO2 in N2 and O2. The NO-dependent relaxation caused by electrical field stimulation (EFS) and acetylcholine (ACh) was studied, and the amplitude and duration of relaxation evaluated. Results: The amplitude of relaxation induced by EFS was significantly decreased under physiological oxygen tension conditions (P < 0.01). The duration of the relaxant response induced by EFS and ACh was significantly prolonged in physiological oxygen tension conditions than in high oxygen tension (P < 0.01). However, there was no correlation between the duration of relaxation induced by EFS and each physiological oxygen tension level. The duration of relaxation induced by ACh was most prolonged at 60,69 mmHg oxygen tension. Conclusion: Physiologically, the effect of NO may last longer than was previously thought. In addition, it would seem that there is an optimal physiological oxygen tension for maximum ACh-induced relaxation. [source] Effect of human chorionic gonadotrophin on in vitro contractions of stimulated detrusor muscle strips of female ratsJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2009Diaa E. E. Rizk Abstract Aims:, We studied the effect of human chorionic gonadotrophin (hCG) on the in vitro detrusor muscle contractions in female rats. Methods:, Two adjacent detrusor muscle strips from the bladder dome of 18 female Wistar rats (230,250 gm) were mounted in an organ bath for the recording of isometric tension. Carbachol (10,9,10,3 M), ,,, methylene adenosine 5,-triphosphate (ATP) (10,9,10,3 M) and potassium chloride (KCl) (10,4,10,3 M) were applied (n = 6 × 3 groups). Concentration-response curves, before and after the addition of hCG (100 iu/mL) or oxybutynin (10,5 M) to either muscle strip, were compared. Results:, All curves were displaced to the right by hCG in a concentration-dependent manner with significant inhibition of contractions induced by carbachol (P < 0.001) and KCl (P = 0.016) but not those induced by ,,,-methylene ATP (P = 0.4). Estimated order of potency of inhibition was carbachol>KCl>,,,-methylene ATP. The overall inhibitory effect of hCG was significantly less than oxybutynin (P < 0.001). Conclusions:, hCG significantly inhibited in vitro detrusor contractions induced by depolarization (KCl) and cholinergic (carbachol) but not purinergic (,,,-methylene ATP) stimulation in a dose-dependent manner in female rats. [source] Inhibition of p38 MAPK improves intestinal disturbances and oxidative stress induced in a rabbit endotoxemia modelNEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2010S. Gonzalo Abstract Background, Lipopolysaccharide (LPS) decreases intestinal contractility and induces the release of reactive oxygen species, which play an important role in the pathogenesis of sepsis. p38 mitogen-activated protein kinase (MAPK) can be activated by a variety of stimuli such as LPS. The aims of this study were: (i) to investigate the role of p38 MAPK in the effect of LPS on (a) the acetylcholine, prostaglandin E2 and KCl-induced contractions of rabbit duodenum and (b) the oxidative stress status; (ii) to localize the active form of p38 in the intestine. Methods, Rabbits were injected with (i) saline, (ii) LPS, (iii) SB203580, a specific p38 MAPK inhibitor or (iv) SB203580 + LPS. Duodenal contractility was studied in an organ bath. SB203580 was also tested in vitro. The protein expression of p-p38 and total p38 was measured by Western blot and p-p38 was localized by inmunohistochemistry. The formation of products of oxidative damage to proteins (carbonyls) and lipids (MDA+4-HDA) was quantified in intestine and plasma. Key Results, ACh, PGE2 and KCl-induced contractions decreased with LPS. LPS increased phospho-p38 expression and the levels of carbonyls and MDA+4-HDA. SB203580 blocked the effect of LPS on the ACh, PGE2 and KCl-induced contractions in vivo and in vitro and the levels of carbonyls and MDA+4-HDA. P-p38 was detected in neurons of the myenteric plexus and smooth muscle cells of duodenum. Conclusions & Inferences, Lipopolysaccharide decreases the duodenal contractility in rabbits and increases the production of free radicals. p38 MAPK is a mediator of these effects. [source] Cell-free supernatants of Escherichia coli Nissle 1917 modulate human colonic motility: evidence from an in vitro organ bath studyNEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2009F. Bär Abstract, Clinical studies have shown that probiotics influence gastrointestinal motility, e.g. Escherichia coli Nissle 1917 (EcN) (Mutaflor®) proved to be at least as efficacious as lactulose and more potent than placebo in constipated patients. As the underlying mechanisms are not clarified, the effects of EcN culture supernatants on human colonic motility were assessed in vitro. Human colonic circular smooth muscle strips (n = 94, 17 patients) were isometrically examined in an organ bath and exposed to different concentrations of EcN supernatants. Contractility responses were recorded under (i) native conditions, (ii) electrical field stimulation (EFS), (iii) non-adrenergic non-cholinergic conditions, and (iv) enteric nerve blockade by tetrodotoxin (TTX). As concentrations of acetic acid were increased in EcN supernatants, contractility responses to acetic acid were additionally tested. EcN supernatants significantly increased the maximal tension forces both at low and high concentrations. Neither blockade of both adrenergic and cholinergic nerves nor application of TTX abolished these effects. EFS-induced contractility responses were not altered after exposure to EcN supernatants. Acetic acid elicited effects comparable to EcN supernatants only under TTX conditions. EcN supernatants modulate in vitro contractility of the human colon. As neither partial nor TTX blockade of enteric nerves abolished these effects, EcN supernatants appear to enhance colonic contractility by direct stimulation of smooth muscle cells. Active metabolites may include other substances than acetic acid, as acetic acid only partially resembled the effects elicited by EcN supernatants. The data provide a rationale for therapeutical application of probiotics in gastrointestinal motility disorders. [source] Nitric oxide mediates the inhibitory effect of ethanol on the motility of isolated longitudinal muscle of proximal colon in ratsNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2007S. L. Wang Abstract, The aim of the present study was to investigate the effect of ethanol on colon motility in rats and to test the possibility that nitric oxide (NO) mediates this effect. Proximal colon longitudinal muscle strips (LM) (8 × 3 mm) cut parallel to the longitudinal muscle fibres of the colon were isolated and mounted in an organ bath. Ethanol (0.57, 0.87 and 1.30 mmol L,1) dose-dependently inhibited the motility of LM. Longitudinal muscle strips from female rats were more sensitive to the inhibitory effect of ethanol than that from male rats. L-NAME (N -nitro- l -arginine methyl ester) (100 ,mol L,1), AG (aminoguanidine) (10 ,mol L,1), ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one) (10 ,mol L,1) and PTIO (2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide) (200 ,mol L,1) partly blocked the inhibitory effect of ethanol on LM. Pretreatment with L-NAME, AG, ODQ and PTIO abolished the sex difference of the inhibitory effect of ethanol on LM. Tetrodotoxin (TTX) (10 ,mol L,1) partly blocked the inhibitory effect but did not influence the sex difference. The relaxation of LM induced by SNP (sodium nitroprusside) (0.1,10 ,mol L,1) in female rats was greater than that in male rats. In conclusion, ethanol inhibited the colon motility in vitro. This inhibitory effect on LM was mediated by NO through the iNOS , NO , cGMP pathway. [source] Autonomous contractile activity in the isolated rat bladder is modulated by a TRPV1 dependent mechanism,NEUROUROLOGY AND URODYNAMICS, Issue 3 2007Thomas Gevaert Abstract Aims Resiniferatoxin (RTX), a vanilloid compound and agonist of the transient receptor potential channel 1 (TRPV1), is known for its beneficial effects on neurogenic detrusor overactivity. The mainstream rationale for its use is the desensitization of TRPV1 on sensory bladder afferents. However, recent findings showed that TRPV1 is present in other cell types in the bladder. To eliminate the effects of RTX on spinal and central neural circuits, we investigated autonomous contractility in normal and neurogenic rat bladders after treatment with RTX. Methods Female Wistar rats were made paraplegic at vertebral level T8,T9. Animals were intravesically pre-treated with vehicle (ethanol 5%) or RTX (100 nM) and sacrificed after 72 hr. Each bladder was excised and placed in a heated organ bath, where intravesical pressures were measured. Effects on contractile parameters of intravesical volume load, the non-selective muscarinic receptor agonist carbachol (CA) and electrical stimulation (ES) of nerves were studied in both groups. Results In RTX-treated normal bladders we found shorter contractions with higher amplitude than in control bladders (P,<,0.05). In RTX-treated neurogenic bladders the amplitude and duration of autonomous contractions were increased compared with controls (P,<,0.05). Furthermore RTX induced an increased response to CA and to ES (P,<,0.05). Conclusions RTX significantly affected the properties of autonomous bladder contractile activity. This provides evidence for local effects of RTX on bladder contractile activity, which are not mediated by afferent neural pathways and which may contribute to the beneficial effects on detrusor overactivity. TRPV1 and TRPV1+ cells seem to play an important role in (autonomous) bladder contractility. Neurourol. Urodynam. 26:424,432, 2007. © 2006 Wiley-Liss, Inc. [source] Comparison study of autonomous activity in bladders from normal and paraplegic rats,,NEUROUROLOGY AND URODYNAMICS, Issue 4 2006Thomas Gevaert Abstract Aim To identify differences in the pattern of pressure generated by isolated bladders from normal and paraplegic rats. Materials and Methods Nine female Wister rats were made paraplegic by spinal cord transsection at the vertebral level T8-T9 and sacrificed between D21 and D28. A further group (n,=,9) was used as a control group. Each bladder was excised and placed in an organ bath where intravesical pressures were measured. Pressure changes were divided in two well-defined groups: macro-transients and spikes. The effects of intravesical volume load and muscarinic (M) agonists were studied. Results We demonstrated a higher frequency, a longer duration, and a higher variance of duration in macro-transients in the neurogenic group. Intravesical volume load influenced the amplitude and frequency of macro-transients in both groups similarly. The effects of the muscarinic (M2)-selective agonist arecaďdine were different in neurogenic bladder; the effects of the non-selective muscarinic (M)-agonist carbachol were similar in both groups. Conclusion We showed that the pattern of autonomous activity was significantly different between normal and neurogenic rat bladders. We also found evidence for alterations in the muscarinic response of isolated neurogenic rat bladders. This model offers an exciting new research tool to evaluate the detrusor activity in neurogenic and normal conditions. Neurourol. Urodynam. © 2006 Wiley-Liss, Inc. [source] Alteration of urothelial-mediated tone in the ischemic bladder: Role of eicosanoids,NEUROUROLOGY AND URODYNAMICS, Issue 3 2004Kazem M. Azadzoi Abstract Aims Previously we showed that ischemia alters bladder smooth muscle contractility in the rabbit. This study investigates the role of urothelium and eicosanoid-release in ischemic bladder smooth muscle instability. Materials and Methods Male New Zealand white rabbits were divided into treated (n,=,12) and age-matched control (n,=,10) groups. The treated group underwent balloon endothelial injury of the iliac arteries, and then received 4 weeks of cholesterol diet, followed by 4 weeks of regular diet. The control group received a regular diet for 8 weeks. After 8 weeks, blood flow for both the iliac arteries and the bladder as well as bladder oxygen tension were recorded. In one-half of each ischemic and control bladder, the urothelium was removed. Bladder tissues were processed for organ bath and enzyme-immunoassay (EIA) of prostaglandins (PGs) and leukotrienes (LTs). Results A significant decrease in iliac arterial blood flow, bladder wall blood flow, and bladder oxygen tension was found in the treated group. Bladder ischemia increased the frequency and amplitude of baseline spontaneous smooth muscle contractility. Ischemic tissues with urothelium (Uro+) demonstrated significant increases in the contractile response to electrical field stimulation (EFS) and carbachol relative to control Uro+ tissues. Urothelial removal increased smooth muscle contraction in the control tissues but had no significant effect in the ischemic/hypoxic tissues. Contraction of control tissues without urothelium (Uro,) was similar to contraction of ischemic Uro+ tissues. Contractions of ischemic Uro+ and control Uro, tissues were unchanged after treatment with the cyclooxygenase (COX) inhibitor indomethacin, while they were significantly reduced by the 5-lipoxygenase (5-LO) inhibitor NDGA. EIA showed no change in PGs release from the ischemic urothelium, but significant increase in PGF2-, and thromboxane A2 release from the ischemic suburothelial tissue. Ischemia increased the release of LTB4, LTC4, and LTE4 from both urothelium and suburothelial tissue. Conclusions Our studies suggest loss of urothelial-mediated tone and LTs-mediated smooth muscle instability in the chronically ischemic/hypoxic bladder. Neurourol. Urodynam. 23:258,264, 2004. Published 2004 Wiley-Liss, Inc. [source] The Effect of Ovariectomy on Rat Vaginal Tissue Contractility and HistomorphologyTHE JOURNAL OF SEXUAL MEDICINE, Issue 2 2006F. Fatih Önol MD ABSTRACT Introduction., Ovarian hormones have an important role in age-related genital arousal disorders; however, our knowledge regarding possible vaginal wall morphology and contractility changes in low-hormonal states is limited. Aims., To investigate morphological and functional alterations in the vaginal tissue in a rat ovariectomy model and to show the differences between proximal and distal vagina. Methods., Six weeks following ovariectomy, vaginal tissues were examined under light and electron microscopy. Circularly cut distal and proximal tissues were studied in the organ bath under isometric tension and compared with age-matched controls. Contractile responses to electrical field stimulation (EFS), phenylephrine, carbachol, and the effects of alpha-1 and alpha-2 blockade on EFS-induced contractility were investigated. Relaxation responses to EFS and vardenafil were investigated in precontracted strips. Main Outcome Measures., Differences between control and ovariectomy groups in terms of vaginal tissue contractility and histomorphological properties. Results., Distal vagina showed different epithelial characteristics and a better-developed muscularis compared with proximal vagina. Ovariectomy caused thinning of the epithelium, severe degeneration in epithelial architecture, and smooth muscle atrophy. Contraction and relaxation responses of distal strips were significantly lower in ovariectomized rats. Contractile responses to neuropharmacological stimulation were insignificant in proximal strips of both groups. EFS-induced contractions in distal strips diminished significantly after alpha-1 and alpha-2 adrenergic blockade. EFS caused frequency-dependent relaxation responses in precontracted distal strips, which were significantly decreased after nitric oxide synthase inhibition. Conclusions., Ovariectomy causes significant alteration in rat vaginal tissue morphology and contractility. Contraction and relaxation responses of distal vagina are significantly greater compared with morphologically distinct proximal vagina. Alpha-1 and alpha-2 receptors are the main mediators of contraction in distal rat vaginal tissue whereas nitric oxide pathway may have at least a partial role in relaxation. Main mediators of the rat vaginal tissue relaxation and the effect of ovariectomy on this regulation are yet to be defined. Önol FF, Ercan F, and Tarcan T. The effect of ovariectomy on rat vaginal tissue contractility and histomorphology. J Sex Med 2006;3:233,241. [source] Resident Macrophages are Involved in Intestinal Transplantation-Associated Inflammation and Motoric Dysfunction of the Graft MuscularisAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2007N. Schaefer Gut manipulation and ischemia/reperfusion evoke an inflammatory response within the intestinal muscularis that contributes to dysmotility. We hypothesize that resident macrophages play a key role in initiating the inflammatory cascade. Isogenic small bowel transplantation was performed in Lewis rats. The impact of recovery of organs on muscularis inflammation was investigated by comparing cold whole-body perfusion after versus prior to recovery. The role of macrophages was investigated by transplantation of macrophage-depleted gut. Leukocytes were counted using muscularis whole mounts. Mediator expression was determined by real-time RT-PCR. Contractility was assessed in a standard organ bath. Both organ recovery and ischemia/reperfusion induced leukocyte recruitment and a significant upregulation in IL-6, MCP-1, ICAM-1 and iNOS mRNAs. Although organ recovery in cold ischemia prevented early gene expression, peak expression was not changed by modification of the recovery technique. Compared to controls, transplanted animals showed a 65% decrease in smooth muscle contractility. In contrast, transplanted macrophage-depleted isografts exhibited significant less leukocyte infiltration and only a 19% decrease in contractile activity. In summary, intestinal manipulation during recovery of organs initiates a functionally relevant inflammatory response within the intestinal muscularis that is massively intensified by the ischemia reperfusion injury. Resident muscularis macrophages participate in initiating this inflammatory response. [source] An evaluation of laparoscopic tissue harvesting for human adult urological smooth muscle physiological experimentationBJU INTERNATIONAL, Issue 3 2005John F. Bolton OBJECTIVE To evaluate the properties of laparoscopically harvested bladder neck and ureteric smooth muscle, compared with tissue obtained at open surgery. MATERIALS AND METHODS Bladder neck was harvested from patients undergoing open (eight) or laparoscopic radical prostatectomy (11). Ureter was obtained from patients undergoing nephrectomy (laparoscopic or open) and cystectomy (open only); obtained openly from 16 and laparoscopically from seven. Muscle strips dissected from these samples were perfused in a Brading-Sibley organ bath, and stimulated using standard agonists (100 µmol/L carbachol for bladder neck, 100 mmol/L KCl-enriched Krebs' solution for ureteric muscle). Tensions produced were recorded using strain gauges and analysed using data-acquisition software. Results were compared by a two-tailed Fisher's exact test to determine significance. RESULTS Openly harvested bladder neck muscle strips from six patients showed a measurable response to the standard agonist. Laparoscopically harvested bladder neck strips from only two patients showed any measurable response. Openly harvested ureteric muscle strips from 12 patients responded to K-enriched solution, while one patient's laparoscopically harvested strips responded to stimulation. This difference was significant in both tissue groups separately (P < 0.025). Histological evaluation identified no specific differences between openly and laparoscopically harvested tissue. CONCLUSION The yield of smooth muscle available for research is significantly less when the resection is laparoscopic; this might be a result of diathermy damage at a subcellular level. With the increasing use of the laparoscopic approach in urological surgery, the effect on tissue availability for human smooth muscle physiological study is important to researchers in this field. [source] Effect of chronic renal failure on the purinergic responses of corpus cavernosal smooth muscle in rabbitsBJU INTERNATIONAL, Issue 6 2002H. Kilicarslan Objective ,To examine purinergic relaxation responses in chronic renal failure (CRF) in an experimental rabbit model, and thus evaluate the possible involvement of the purinergic system in erectile dysfunction with CRF. Materials and methods ,The relaxant effects of ATP were measured in strips of corpus cavernosum smooth muscle taken from control and CRF rabbits. CRF was induced in New Zealand white rabbits as previously described. Penises were excised from CRF rabbits 4 weeks after inducing uraemia. In an organ bath the strips from controls and CRF rabbit corpus cavernosum were pre-contracted with phenylephrine and increasing doses of adenosine and ATP added. Results ,In the pre-contracted rabbit cavernosal tissue the relaxations induced by adenosine and ATP were unchanged in CRF. Conclusion ,The lack of any relaxant effect of adenosine or ATP on the relaxation of cavernosal smooth muscle in rabbits with CRF might be because the relaxant effects of these agents are endothelium-independent and the endothelial purinergic receptor density was unchanged in CRF. [source] 5-HT4 receptors on cholinergic nerves involved in contractility of canine and human large intestine longitudinal muscleBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2000N H Prins 5-HT4 receptors mediate circular muscle relaxation in both human and canine large intestine, but this phenomenon alone can not explain the improvement in colonic motility induced by selective 5-HT4 receptor agonists in vivo. We set out to characterize 5-HT4 receptor-mediated effects in longitudinal muscle strips of canine and human large intestine. Electrical field stimulation (EFS) was applied providing submaximal isotonic contractions. L -NOARG (0.1 mM) was continuously present in the organ bath to preclude nitric oxide-induced relaxation to EFS. The selective 5-HT4 receptor agonist prucalopride (0.3 ,M) enhanced EFS-evoked contractions, that were antagonized in both preparations by the selective 5-HT4 receptor antagonist GR 113808 (0.1 ,M). The prucalopride-induced increase was present in canine ascending and descending colon, but absent in rectum. Regional differences in response to prucalopride were not observed in human ascending and sigmoid colon and rectum. Incubation with atropine (1 ,M) or tetrodotoxin (0.3 ,M) inhibited EFS-induced contractions, which were then unaffected by prucalopride (0.3 ,M) in both tissues. In the presence of methysergide (3 ,M; both tissues) and granisetron (0.3 ,M; only human tissues), 5-HT (0.3 ,M) enhanced EFS-induced contractions, an effect that was antagonized by GR 113808 (0.1 ,M). In the presence of atropine or tetrodotoxin, EFS-induced contractions were inhibited, leaving 5-HT (0.3 ,M) ineffective in both preparations. This study demonstrates for the first time that in human and canine large intestine, 5-HT4 receptors are located on cholinergic neurones, presumably mediating facilitating release of acetylcholine, resulting in enhanced longitudinal muscle contractility. This study and previous circular muscle strip studies suggest that 5-HT4 receptor agonism facilitates colonic propulsion via a coordinated combination of inhibition of circumferential resistance and enhancement of longitudinal muscle contractility. British Journal of Pharmacology (2000) 131, 927,932; doi:10.1038/sj.bjp.0703615 [source] Isolated airways from current smokers are hyper-responsive to histamineCLINICAL & EXPERIMENTAL ALLERGY, Issue 7 2001D. T. Schmidt Epidemiological studies suggest that bronchial hyper-responsiveness (BHR) and elevated levels of serum IgE are more frequently found in current smokers than in ex-smokers. Since elevated serum IgE is associated with BHR under both in vivo and in vitro conditions, we aimed to assess whether smoking affects BHR independently from IgE. Lung resection material was obtained from 27 current smokers and 11 non-smokers with low serum IgE (< 100 U/mL). Peripheral airways were cut into rings and incubated overnight in the presence (passively sensitized) or absence (non-sensitized) of serum containing IgE levels above 250 U/mL. Isometric contractile responses to histamine were assessed in the organ bath. Compared with non-smokers, isolated airways from smokers showed significantly increased responses to histamine (P < 0.05, anova). Passive sensitization enhanced responses in both groups by about the same amount (P < 0.05, both). In patients with low serum IgE current smoking is associated with increased bronchial responsiveness to histamine in vitro, which can be further enhanced by passive sensitization. These findings suggest that both smoking and serum IgE contribute to non-specific airway hyper-responsiveness. [source] Serum immunoglobulin E levels predict human airway reactivity in vitroCLINICAL & EXPERIMENTAL ALLERGY, Issue 2 2000Schmidt Background Airway hyperresponsiveness to non-specific stimuli is one characteristic feature of airway diseases such as bronchial asthma and chronic bronchitis. Until now, studies aiming to demonstrate a relationship between in vivo conditions associated with airway hyperreactivity and in vitro airway responsiveness have been inconclusive. Objective Since serum immunoglobulin (Ig) E is believed to be one determinant of airway reactivity in vivo, we studied whether in vitro airway reactivity in lung resection material from patients with elevated levels of serum IgE was increased as compared with patients with undetectable IgE. By this approach, we aimed to elucidate the role of circulating IgE for bronchial smooth muscle reactivity in vitro. Methods Bronchial rings from nine patients with total serum IgE levels above 200 U/mL and 10 patients with total serum IgE levels below 10 U/mL were passively sensitized, i.e. incubated overnight with buffer or sensitizing serum containing high levels of total IgE (> 250 U/mL). Afterwards, contractile responses to histamine were assessed in the organ bath. Results Histamine responsiveness was significantly increased in airways obtained from patients with IgE levels above 200 U/mL as compared with airways from patients with IgE levels below 10 U/mL (P < 0.05). Passive sensitization of bronchi from patients with low IgE significantly increased histamine responsiveness, as compared with non-sensitized controls from the same patients (P < 0.05). In contrast, passive sensitization of airways from patients with elevated IgE did not further increase responsiveness. There was no difference in histamine reactivity between non-passively sensitized and passively sensitized tissue preparations from patients with IgE above 200 U/mL and passively sensitized tissues from patients with IgE below 10 U/mL. Conclusion Our findings reveal that elevated levels of serum IgE predict airway hyperresponsiveness to histamine in vitro. At the same time, they indicate that the in vitro model of passive sensitization, in addition to its ability to induce allergen responses, also mimics conditions of non-specific airway hyperreactivity, which are relevant under in vivo conditions. [source] Cysteinyl leukotrienes and leukotriene B4 mediate vasoconstriction to arginine vasopressin in rat basilar arteryCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2005Cristina C Trandafir Summary 1.,Arginine vasopressin (AVP) has been reported to be involved in the development of cerebral vasospasm after haemorrhage and cerebral oedema following ischaemia. Endogenously produced 5-lipoxygenase metabolites are able to contract isolated endothelium-preserved arterial strips and modulate vascular permeability. The present study addresses the role of 5-lipoxygenase and its products, namely cysteinyl leukotrienes (CysLTs) and leukotriene (LT) B4, in the contraction induced by AVP in rat basilar artery. 2.,Contractile responses to LTD4, LTC4, LTB4 or AVP were assessed in spiral preparations of rat endothelium-intact basilar artery. Contractions to AVP were determined in the absence or presence of 5-lipoxygenase inhibitors or CysLT1 or BLT receptor antagonists. Contractile responses to leukotrienes and AVP are expressed as a percentage of the contraction induced by 80 mmol/L KCl. 3.,Leukotriene D4, LTC4 and LTB4 acted as vasoconstrictor agents in rat basilar artery, causing contractions (all at concentrations of 1 µmol/L) of 42 ± 13, 54 ± 15 and 25 ± 6% of the response to 80 mmol/L KCl, respectively. A concentration,response curve was constructed for AVP over the range 1 pmol/L to 10 nmol/L and an EC50 value of 0.19 ± 0.02 nmol/L (n = 30) was determinted. The presence of the 5-lipoxygenase inhibitors ZM 230487 (10 nmol/L and 0.1 and 1 µmol/L) and AA 861 (1, 3, 10, and 30 µmol/L), the CysLT1 receptor antagonist MK 571 (3, 10 and 30 µmol/L) or the BLT receptor antagonists CP 105696 and LY 255283 (3, 10 and 30 µmol/L for both) in the organ bath significantly attenuated the contractions induced by AVP in rat basilar artery (P < 0.05). 4.,The experimental results of the present study provide the first evidence for the involvement of CysLTs and LTB4 in the in vitro constriction induced by AVP in rat basilar artery. In the context of previously reported involvement of AVP in the development of cerebral vasospasm and oedema, the present study draws attention to the potential role played by the 5-lipoxygenase pathway in these pathological processes. [source] Estimation of endogenous adenosine activity at adenosine receptors in guinea-pig ileum using a new pharmacological methodACTA PHYSIOLOGICA, Issue 2 2010K. F. Nilsson Abstract Aim:, Adenosine modulates neurotransmission and in the intestine adenosine is continuously released both from nerves and from smooth muscle. The main effect is modulation of contractile activity by inhibition of neurotransmitter release and by direct smooth muscle relaxation. Estimation of adenosine concentration at the receptors is difficult due to metabolic inactivation. We hypothesized that endogenous adenosine concentrations can be calculated by using adenosine receptor antagonist and agonist and dose ratio (DR) equations. Methods:, Plexus-containing guinea-pig ileum longitudinal smooth muscle preparations were made to contract intermittently by electrical field stimulation in organ baths. Schild plot regressions were constructed with 2-chloroadenosine (agonist) and 8-(p -sulfophenyl)theophylline (8-PST; antagonist). In separate experiments the reversing or enhancing effect of 8-PST and the inhibiting effect of 2-chloroadenosine (CADO) were analysed in the absence or presence of an adenosine uptake inhibitor (dilazep), and nucleoside overflow was measured by HPLC. Results:, Using the obtained DR, baseline adenosine concentration was calculated to 28 nm expressed as CADO activity, which increased dose dependently after addition of 10,6 m dilazep to 150 nm (P < 0.05). HPLC measurements yielded a lower fractional increment (80%) in adenosine during dilazep, than found in the pharmacological determination (440%). Conclusion:, Endogenous adenosine is an important modulator of intestinal neuro-effector activity, operating in the linear part of the dose,response curve. Other adenosine-like agonists might contribute to neuromodulation and the derived formulas can be used to calculate endogenous agonist activity, which is markedly affected by nucleoside uptake inhibition. The method described should be suitable for other endogenous signalling molecules in many biological systems. [source] Aerobic exercise acutely improves insulin- and insulin-like growth factor-1-mediated vasorelaxation in hypertensive ratsEXPERIMENTAL PHYSIOLOGY, Issue 5 2010Ai-Lun Yang Limited information is available concerning the effects of aerobic exercise on vasorelaxation in hypertension. The aim of this study was to investigate the effects of a single bout of aerobic exercise on insulin- and insulin-like growth factor-1 (IGF-1)-induced vasorelaxation in hypertensive rats. Four-month-old spontaneously hypertensive rats were randomly divided into a sedentary group (SHR) and an exercise group (SHR+Ex) subjected to a single bout of aerobic exercise conducted by treadmill running at 21 m min,1 for 1 h. Age-matched Wistar,Kyoto rats were used as a normotensive control group (WKY). Insulin- and IGF-1-induced vasorelaxant responses in the three groups were evaluated by using isolated aortic rings, with or without endothelial denudation, in organ baths. Possible roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS) involved in the NO-dependent vasorelaxation were examined by adding selective inhibitors. The role of superoxide was also clarified by adding superoxide dismutase (SOD). In addition, the endothelium-independent vascular responses to sodium nitroprusside (SNP), a NO donor, were examined. The insulin- and IGF-1-induced vasorelaxation was significantly (P < 0.05) decreased in the SHR group compared with the WKY group. This decreased response in SHR was improved by exercise. These vasorelaxant responses among the three groups became similar after endothelial denudation and pretreatment with the PI3K inhibitor, NOS inhibitor or SOD. Also, no difference among groups was found in the SNP-induced vasorelaxation. We concluded that a single bout of aerobic exercise acutely improves insulin- and IGF-1-mediated vasorelaxation in an endothelium-dependent manner in hypertensive rats. [source] Hydrogen,potassium ATPase inhibitors induce relaxation on rabbit prostatic strips in vitroINTERNATIONAL JOURNAL OF UROLOGY, Issue 11 2002Ihsan Bagcivan Summary Background : To determine the relaxant effect of omeprazole and lansaprazole, hydrogen,potassium (H+,K+) ATPase inhibitors, on rabbit prostatic tissue in vitro. Methods : Male New Zealand white rabbits were sacrificed and their prostatic tissues were removed. The prostatic stromal strips were mounted in organ baths and relaxation responses were obtained in precontracted tissues with phenylephrine, carbachol and potassium chloride (KCl). Relaxation responses were controlled in the presence of various antagonists to explain the mechanism for relaxation exerted by omeprazole and lansaprazole. Results : Omeprazole and lansaprazole caused similar relaxation responses in the prostatic strips precontracted with phenylephrine, carbachol and KCl. The addition of prostaglandin synthase inhibitor indomethacin, nitric oxide synthase inhibitor L-NAME, potassium channel blockers, glibenclamide and tetraethylammonium into the organ baths did not change the relaxations induced by omeprazole and lansaprazole in vitro. Conclusion : Omeprazole and lansaprazole cause a relaxation in prostatic stromal tissue precontracted with phenyephrine, carbachol and KC1 in vitro. This relaxant effect is independent of H+,K+ ATPase inhibition. Additionally, cyclooxygenase and nitric oxide pathways do not contribute to this relaxant effect. Further studies are required to determine whether these drugs may have a beneficial effect in the non-operative treatment of benign prostatic hyperplasia. [source] How important is stimulation of ,-adrenoceptors for melatonin production in rat pineal glands?JOURNAL OF PINEAL RESEARCH, Issue 4 2002V. A. Tobin The objective of this study was to determine the role of , -adrenoceptors in melatonin production by rat pineal gland. Pineal glands were isolated from adult male rats and maintained in organ baths. The perfusate was sampled every 5 min, stored, and later assayed for melatonin. Exposure to norepinephrine (10 ,M) or the , -adrenoceptor agonist orciprenaline (2,10 ,M) increased the glands' production of melatonin. The time courses of melatonin production in response to these agonists were unaffected by the rats' pretreatment in vivo with the , -adrenoceptor antagonist prazosin (2 mg/kg i.p., three times). Rats that had had their superior cervical ganglia removed were primed with either orciprenaline (2 mg/kg i.p) or both orciprenaline and phenylephrine (1 mg/kg i.p) 1 hr before decapitation. Exposure of the pineal glands from these rats to orciprenaline evoked melatonin release that was similar in each group. These results lend weight to the suggestion that the marked potentiation by , -adrenoceptor agonists of the stimulation of cAMP and N-acetyltransferase (NAT) by , -adrenoceptor agonists, demonstrated most readily in cultured glands or dispersed rat pinealocytes, does not carry over into significant augmentation of melatonin production in intact pineal glands. [source] Effect of otilonium bromide on contractile patterns in the human sigmoid colonNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2010D. Gallego Abstract Background, The mechanism of action of the spasmolytic compound otilonium bromide (OB) on human colonic motility is not understood. The aim of our study was to characterize the pharmacological effects of OB on contractile patterns in the human sigmoid colon. Methods, Circular sigmoid strips were studied in organ baths. Isolated smooth muscle cells from human sigmoid colon were examined using the calcium imaging technique. Key Results, Otilonium bromide inhibited by 85% spontaneous non-neural rhythmic phasic contractions (RPCs), (IC50 = 49.9 nmol L,1) and stretch-induced tone (IC50 = 10.7 nmol L,1) with maximum effects at micromolar range. OB also inhibited by 50% both on- (IC50 = 38.0 nmol L,1) and off- contractions induced by electrical stimulation of excitatory motor neurons. In contrast, the inhibitory latency period prior to off -contractions was unaffected by OB. OB inhibited acetylcholine-, substance P-, and neurokinin A-induced contractions. The L-type Ca2+ channel agonist BayK8644 reversed the effects of OB on RPCs, on- and off -contractions. Hexamethonium, atropine, the NK2 antagonist, or depletion of intracellular Ca2+ stores by thapsigargin did not prevent the inhibitory effect of OB on RPCs and electrical contractions. KCl-induced calcium transients in isolated smooth muscle cells were also inhibited by OB (IC50 = 0.2 ,mol L,1). Conclusions & Inferences, Otilonium bromide strongly inhibited the main patterns of human sigmoid motility in vitro by blocking calcium influx through L-type calcium channels on smooth muscle cells. This pharmacological profile may mediate the clinically observed effects of the drug in patients with irritable bowel syndrome. [source] The herbal preparation STW5 (lberogast®) has potent and region-specific effects on gastric motilityNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2004B. Hohenester Abstract, Functional dyspepsia (FD) is amongst the most common functional gastrointestinal disorders. Symptomatic treatment includes the use of herbal preparations whose effects on gastric motility are unclear. The present study aimed at investigating the effects of STW 5 (Iberogast®), a fixed combination of hydroethanolic herbal extracts, on gastric motility in vitro. Muscle strips from guinea-pig gastric fundus, corpus and antrum were set up in organ baths either in circular or longitudinal orientation. Addition of ethanol-free STW 5 to the organ baths (32,512 ,g mL,1) dose-dependently evoked a sustained and reversible relaxation of circular and longitudinal fundus and corpus muscle strips without changes in phasic activity. In contrast, antral muscle strips responded to STW 5 with a significant increase in the contractile force of phasic contractions without changes in tone. All effects were resistant to tetrodotoxin (0.5 ,mol L,1), atropine (1 ,mol L,1), , -conotoxin GVIA (0.5 ,mol L,1), capsaicin (1 ,mol L,1) or l -NAME (100 ,mol L,1), suggesting that neither nerves nor nitric oxide pathways were involved. These data demonstrate that STW 5 profoundly alters gastric motility in a region-specific but not layer-specific manner and thus implicates Iberogast® in the treatment of FD patients suffering from motility disorders with impaired fundus accommodation and/or antral hypomotility. [source] Pre-junctional ,2 -adrenoceptors modulation of the nitrergic transmission in the pig urinary bladder neck,NEUROUROLOGY AND URODYNAMICS, Issue 4 2007Medardo Hernández Abstract Aims To investigate the nitric oxide (NO)-mediated nerve relaxation and its possible modulation by pre-junctional ,2 -adrenoceptors in the pig urinary bladder neck. Methods Urothelium-denuded bladder neck strips were dissected, and mounted in isolated organ baths containing a physiological saline solution (PSS) at 37°C and continuously gassed with 5% CO2 and 95% O2, for isometric force recording. The relaxations to transmural nerve stimulation (electrical field stimulation [EFS]) or exogenously applied NO were carried out on strips pre-contracted with 1 µM phenylephrine (PhE) and treated with guanethidine (10 µM) and atropine (0.1 µM), to block noradrenergic neurotransmission and muscarinic receptors, respectively. Results EFS (0.2,1 Hz, 1 msec duration, 20 sec trains, current output adjusted to 75 mA) evoked frequency-dependent relaxations which were abolished by the neuronal voltage-activated Na+ channel blocker tetrodotoxin (TTX, 1 µM). These responses were potently reduced by the nitric oxide synthase (NOS) inhibitor NG -nitro- L -arginine (L-NOARG, 30 µM) and further reversed by the NO synthesis substrate L -arginine (L-ARG, 3 mM). The ,2 -adrenoceptor agonist BHT-920 (2 µM) reduced the electrically evoked relaxations, its effectiveness being higher on the responses induced by low frequency stimulation. BHT-920-elicited reductions were fully reversed by the ,2 -adrenoceptor antagonist rauwolscine (RAW, 1 µM). Exogenous NO (1 µM,1 mM) induced concentration-dependent relaxations which were not modified by BHT-920, thus eliminating a possible post-junctional modulation. Conclusions These results indicate that NO is involved in the non-adrenergic non-cholinergic (NANC) inhibitory neurotransmission in the pig urinary bladder neck, the release of NO from intramural nerves being modulated by pre-junctional ,2 -adrenoceptor stimulation. Neurourol. Urodynam. 26:578,583, 2007. © 2007 Wiley-Liss, Inc. [source] Preconditioning protects the guinea-pig urinary bladder against ischaemic conditions in vitroNEUROUROLOGY AND URODYNAMICS, Issue 7 2003Bruno Lorenzi Abstract Aims To investigate the ability of ischaemic preconditioning (IPC) to protect guinea-pig detrusor from damage caused by a subsequent more prolonged exposure to ischaemic conditions. Materials and Methods Smooth muscle strips were mounted for tension recording in small organ baths continuously superfused with Krebs' solution at 37°C. Ischaemia was mimicked by removing oxygen and glucose from the superfusing solution. Contractile responses to electrical field stimulation (EFS) and carbachol were monitored. Three regimes of preconditioning were examined: 15, 10, and 5 min of ischaemic conditions followed by 15, 10, and 5 min of normal conditions, respectively. Results Without preconditioning, nerve-mediated responses were significantly and proportionally reduced by periods of ischaemic conditions lasting for 45, 60, and 90 min, but recovered fully after exposure to ischaemic conditions for 30 min. The recovery of the responses to EFS was significantly improved in preconditioned strips when the period of ischaemic conditions was 45 or 60 min. However, no significant differences were seen with preconditioning when the period of ischaemic conditions was 90 min. The recovery of responses to carbachol was much greater than for the responses to EFS, and no significant differences were found between control and preconditioned strips. Conclusions It is suggested that in vivo short periods of transient ischaemia may be able to protect the guinea-pig bladder from the impairment associated with longer periods of ischaemia and reperfusion, which might happen in obstructed micturition. Our results also indicate that the phenomenon affects mainly the intrinsic nerves, which are more susceptible to ischaemic damage than the smooth muscle. Neurourol. Urodynam. 22:687,692, 2003. © 2003 Wiley-Liss, Inc. [source] Pharmacological and Functional Characterization of Novel EP and DP Receptor Agonists: DP1 Receptor Mediates Penile Erection in Multiple SpeciesTHE JOURNAL OF SEXUAL MEDICINE, Issue 2 2008Nadia Brugger PhD ABSTRACT Introduction., Despite the widespread use of prostaglandin E1 as an efficacious treatment for male erectile dysfunction for more than two decades, research on prostanoid function in penile physiology has been limited. Aim., To characterize the pharmacological and physiological activity of novel subtype-selective EP and DP receptor agonists. Methods., Radioligand binding and second messenger assays were used to define receptor subtype specificity of the EP and DP agonists. Functional activity was further characterized using isolated human and rabbit penile cavernosal tissue in organ baths. In vivo activity was assessed in rabbits and rats by measuring changes in cavernous pressure after intracavernosal injection of receptor agonists. Main Outcome Measures., Receptor binding and signal transduction, smooth muscle contractile activity, erectile function. Results., In organ bath preparations of human cavernosal tissue contracted with phenylephrine, EP2- and EP4-selective agonists exhibited variable potency in causing relaxation. One of the compounds caused mild contraction, and none of the compounds was as effective as PGE1 (EC50 = 0.23 µM). There was no consistent correlation between the pharmacological profile (receptor binding and second messenger assays) of the EP agonists and their effect on cavernosal tissue tone. In contrast, the DP1-selective agonist AS702224 (EC50 =29 nM) was more effective in relaxing human cavernosal tissue than either PGE1, PGD2 (EC50 = 58 nM), or the DP agonist BW245C (EC50 =59 nM). In rabbit cavernosal tissue, PGE1 and PGD2 caused only contraction, while AS702224 and BW245C caused relaxation. Intracavernosal administration of AS702224 and BW245C also caused penile tumescence in rabbits and rats. For each compound, the erectile response improved with increasing dose and was significantly higher than vehicle alone. Conclusions., These data suggest that AS702224 is a potent DP1-selective agonist that causes penile erection. The DP1 receptor mediates relaxation in human cavernosal tissue, and stimulates pro-erectile responses in rat and rabbit. Thus, rabbits and rats can be useful models for investigating the physiological function of DP1 receptors. Brugger N, Kim NN, Araldi GL, Traish AM, and Palmer SS. Pharmacological and functional characterization of novel EP and DP receptor agonists: DP1 receptor mediates penile erection in multiple species. J Sex Med 2008;5:344,356. [source] Anandamide improves the impaired nitric oxide-mediated neurogenic relaxation of the corpus cavernosum in diabetic rats: involvement of cannabinoid CB1 and vanilloid VR1 receptorsBJU INTERNATIONAL, Issue 6 2007Mehdi Ghasemi OBJECTIVE To investigate the ability of acute administration of the endogenous cannabinoid, anandamide, in vitro to alter the nonadrenegic noncholinergic (NANC)-mediated relaxation of corpus cavernosum (CC) in diabetic rats and the possible role of nitric oxide (NO), as it is well known that erectile dysfunction (ED) affects 35,75% of men with diabetes mellitus and several studies have been conducted to find appropriate strategies for treating diabetes-induced ED. MATERIALS AND METHODS Diabetes was induced in rats by streptozotocin administration and was maintained for 8 weeks. The CC were removed and isolated in organ baths for pharmacological studies. Agonist-evoked or electrical-field stimulation (EFS)-evoked smooth muscle tensions in CC strips from control and diabetic rats were measured. RESULTS The neurogenic relaxation of phenylephrine (7.5 µm)-precontracted isolated CC strips was impaired in diabetic rats. Anandamide (0.3, 1 and 3 µm) enhanced the relaxant responses to EFS in diabetic CC strips in a dose-dependent manner. This effect was antagonized by the selective cannabinoid CB1 receptor antagonist AM251 (1 µm) and the selective vanilloid receptor antagonist capsazepine (3 µm). Concurrent administration of partially effective doses of l -arginine (10 µm) and anandamide (0.3 µm) exerted a synergistic improvement in EFS-induced relaxation of diabetic CC strips (P < 0.001). The relaxant responses to the NO donor, sodium nitroprusside, were similar between diabetic and control groups. CONCLUSION For the first time, we show that acute administration of anandamide, an endogenous cannabinoid, alone or combined with l -arginine can improve nitrergic nerve-mediated relaxation of the CC in diabetic rats. This effect was mediated by cannabinoid CB1 and vanilloid VR1 receptors within the CC. [source] Mechanisms involved in the regulation of bovine pulmonary vascular tone by the 5-HT1B receptorBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010C McKenzie Background and purpose:, 5-HT1B receptors may have a role in pulmonary hypertension. Their relationship with the activity of BKCa, a T-type voltage-operated calcium channel (VOCC) and cyclic nucleotide-mediated relaxation was examined. Experimental approach:, Ring segments of bovine pulmonary arteries were mounted in organ baths in modified Krebs,Henseleit buffer (37oC) under a tension of 20 mN and gassed with 95% O2/5% CO2. Isometric recordings were made using Chart 5 software. Key results:, Contractile responses to 5-HT (10 nM,300 µM) were inhibited similarly by the 5-HT1B receptor antagonist SB216641 (100 nM) and the T-type VOCC blockers mibefradil (10 µM) and NNC550396 (10 µM) with no additive effect between SB216641 and mibefradil. Inhibition by SB216641 was prevented by the potassium channel blocker, charybdotoxin (100 nM). 5-HT1B receptor activation and charybdotoxin produced a mibefradil-sensitive potentiation of responses to U46619. Bradykinin (0.1 nM,30 µM), sodium nitroprusside (0.01 nM,3 µM), zaprinast (1 nM,3 µM), isoprenaline (0.1 nM,10 µM) and rolipram (1 nM,3 µM) produced 50% relaxation of arteries constricted with 5-HT (1,3 µM) or U46619 (30,50 nM) in the presence of 5-HT1B receptor activation, but full relaxation of arteries constricted with U46619, the 5-HT2A receptor agonist 2,5 dimethoxy-4 iodoamphetamine (1 µM) or 5-HT in the presence of 5-HT1B receptor antagonism. Enhanced relaxation of 5-HT-constricted arteries by cGMP-dependent pathways, seen in the presence of the 5-HT1B receptor antagonist, was reversed by charybdotoxin whereas cAMP-dependent relaxation was only partly reversed by charybdotoxin. Conclusions and implications:, 5-HT1B receptors couple to inhibition of BKCa, thus increasing tissue sensitivity to contractile agonists by activating a T-type VOCC and impairing cGMP-mediated relaxation. Impaired cAMP-mediated relaxation was only partly mediated by inhibition of BKCa. [source] | ||||||||||||||||||||||||||||