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Muscle Strips (muscle + strip)

Distribution by Scientific Domains

Medical Sciences	82%
Life Sciences	14%

Kinds of Muscle Strips

longitudinal muscle strip

smooth muscle strip

Selected Abstracts

Effects of extrinsic denervation on innervation with VIP and substance P in circular muscle of rat jejunum,

NEUROGASTROENTEROLOGY & MOTILITY, Issue 7 2008
M. S. Kasparek
Abstract, Extrinsic denervation contributes to enteric motor dysfunction after small bowel transplantation (SBT). Our aim was to determine changes in nonadrenergic, noncholinergic innervation with vasoactive intestinal polypeptide (VIP) and substance P (Sub P) in rat jejunal circular muscle after SBT. Muscle strips were studied in tissue chambers from six groups of rats (n , 6 per group): naïve controls (NC), animals 1 week after anaesthesia/sham celiotomy (SC-1), and 1 and 8 weeks after jejunal and ileal transection/reanastomosis (TA-1, TA-8) and after syngeneic, orthotopic SBT (SBT-1, SBT-8). Response to exogenous VIP and Sub P and their endogenous release during electrical field stimulation (EFS) were studied. Exogenous VIP and Sub P caused a dose-dependent inhibition and stimulation of mechanical activity in all groups respectively (P < 0.05). The responses to VIP and Sub P were decreased (compared to NC) in all groups at 1 and 8 weeks postoperatively. The VIP antagonist ([d - p -Cl-Phe6,Leu17]-VIP) did not prevent the inhibition by exogenous VIP in any group, while the Sub P antagonist ([d -Pro2,d -Trp7,9]-Sub P) prevented the effect of exogenous Sub P in NC, TA-8 and SBT-8 (P < 0.05). Responses to exogenous VIP were unaffected by the nitric oxide synthase inhibitor l - NG -nitro arginine and precontraction of muscle strips with Sub P. Endogenous release of VIP and Sub P during EFS was preserved after SBT. In circular muscle of rat jejunum, changes in neuromuscular transmission with VIP and Sub P during the first 8 weeks after SBT are not mediated by extrinsic denervation. [source]

The herbal preparation STW5 (lberogast®) has potent and region-specific effects on gastric motility

NEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2004
B. 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]

AMP kinase activation with AICAR further increases fatty acid oxidation and blunts triacylglycerol hydrolysis in contracting rat soleus muscle

THE JOURNAL OF PHYSIOLOGY, Issue 2 2005
Angela C. Smith
Muscle contraction increases glucose uptake and fatty acid (FA) metabolism in isolated rat skeletal muscle, due at least in part to an increase in AMP-activated kinase activity (AMPK). However, the extent to which AMPK plays a role in the regulation of substrate utilization during contraction is not fully understood. We examined the acute effects of 5-aminoimidazole-4-carboxamide riboside (AICAR; 2 mm), a pharmacological activator of AMPK, on FA metabolism and glucose oxidation during high intensity tetanic contraction in isolated rat soleus muscle strips. Muscle strips were exposed to two different FA concentrations (low fatty acid, LFA, 0.2 mm; high fatty acid, HFA, 1 mm) to examine the role that FA availability may play in both exogenous and endogenous FA metabolism with contraction and AICAR. Synergistic increases in AMPK ,2 activity (+45%; P < 0.05) were observed after 30 min of contraction with AICAR, which further increased exogenous FA oxidation (LFA: +71%, P < 0.05; HFA: +46%, P < 0.05) regardless of FA availability. While there were no changes in triacylglycerol (TAG) esterification, AICAR did increase the ratio of FA partitioned to oxidation relative to TAG esterification (LFA: +65%, P < 0.05). AICAR significantly blunted endogenous TAG hydrolysis (LFA: ,294%, P < 0.001; HFA: ,117%, P < 0.05), but had no effect on endogenous oxidation rates, suggesting a better matching between TAG hydrolysis and subsequent oxidative needs of the muscle. There was no effect of AICAR on the already elevated rates of glucose oxidation during contraction. These results suggest that FA metabolism is very sensitive to AMPK ,2 stimulation during contraction. [source]

An evaluation of laparoscopic tissue harvesting for human adult urological smooth muscle physiological experimentation

BJU INTERNATIONAL, Issue 3 2005
John 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 human chorionic gonadotrophin on in vitro contractions of stimulated detrusor muscle strips of female rats

JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2009
Diaa 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]

RELAXANT EFFECT OF ADRENOMEDULLIN ON BOVINE ISOLATED IRIS SPHINCTER MUSCLE UNDER RESTING CONDITIONS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2005
Y Uchikawa
SUMMARY 1.,The mechanisms involved in the fine adjustment of iris sphincter muscle tone are largely unknown. The aim of the present study was to clarify the effects of adrenomedullin on the resting tension of the bovine isolated iris sphincter muscle. 2.,The motor activity of the bovine isolated iris sphincter muscle was measured isometrically. The effects of adrenomedullin on resting tension were analysed in the presence of indomethacin. The presence of adrenomedullin mRNA in the preparation was determined by reverse transcription,polymerase chain reaction. Immunolabelling for adrenomedullin was also performed. 3.,Adrenomedullin significantly decreased the resting tension of the muscle. The relaxant effect of adrenomedullin was significantly inhibited by adrenomedullin (22,52), a putative antagonist for the adrenomedullin receptor, or calcitonin gene-related peptide (CGRP) (8,37), a putative antagonist for the CGRP1 receptor. The relaxant effect was almost completely blocked by a combination of adrenomedullin (22,52) and CGRP (8,37). 4.,The relaxant effect of adrenomedullin was also significantly diminished by 2,,5,-dideoxyadenosine, an inhibitor of adenylate cyclase, NG -nitro- l -arginine, an inhibitor of nitric oxide synthesis, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, an inhibitor of soluble guanylate cyclase. 5.,Reverse transcription,polymerase chain reaction analysis showed that adrenomedullin mRNA was expressed in the muscle strip. Immunopositive staining for adrenomedullin was detected in blood vessel cells and in the iris sphincter muscle cells. 6.,These results suggest that adrenomedullin may be an autocrine and paracrine regulator of the resting tension of the iris sphincter muscle. Its biological effects may be due to the direct involvement of adrenomedullin receptors and also to the stimulation of CGRP1 receptors. The stimulation of these receptors by the peptide leads to the activation of adenylate cyclase and soluble guanylate cyclase and subsequent relaxation of the muscle strip. [source]

Relaxant effects of , -adrenergic agonists on porcine and human detrusor muscle

ACTA PHYSIOLOGICA, Issue 2 2005
J. K. Badawi
Abstract Aim:, Relaxant effects of different , -adrenoceptor agonists on porcine and human detrusor were examined. Thus, the , -adrenoceptor subtype mainly responsible for relaxation in the detrusor muscle of pigs was characterized. Additionally, different effects of several , -agonists in both species were shown. Methods:, Experiments were performed on muscle strips of porcine and human detrusor suspended in a tissue bath. The relaxant effects of the non-selective , -agonist isoprenaline, the selective ,2-agonists procaterol, salbutamol and the selective ,3-agonists BRL 37344, CL 316 243 and CGP 12177 on potassium-induced contraction were investigated. The inhibitory effect of different substances on the maximum contraction and the rank order of potency for endogenous catecholamines was determined in pigs. Furthermore, concentration-relaxation curves were performed for pigs and humans. Results:,Pigs: In the pre-treatment experiments isoprenaline and procaterol showed similar effects. The concentration,response experiments showed that the maximum relaxation induced by procaterol and salbutamol was more than 90%, not significantly different from isoprenaline, whereas the maximum relaxations of CL 316 243, BRL 37344 and CGP 12177 amounted to 68, 70 or 30%, respectively. Rank order of potencies was isoprenaline , adrenaline > noradrenaline. Humans: Isoprenaline, procaterol, salbutamol and CL 316 243 showed a maximum relaxation of 80, 41, 24 and 35% and pD2 values of 6.24, 5.65, 5.48 and 5.55, respectively. Conclusion:,,2-receptors play a main functional role in mediating relaxation of porcine detrusor. Selective ,2- and ,3-agonists similarly relax the human detrusor. Effects were smaller compared with the pig. [source]

Effect of dopamine on rat diaphragm apoptosis and muscle performance

EXPERIMENTAL PHYSIOLOGY, Issue 4 2006
Janet D. Pierce
The purpose of this study was to determine whether dopamine (DA) decreases diaphragm apoptosis and attenuates the decline in diaphragmatic contractile performance associated with repetitive isometric contraction using an in vitro diaphragm preparation. Strenuous diaphragm contractions produce free radicals and muscle apoptosis. Dopamine is a free radical scavenger and, at higher concentrations, increases muscle contractility by simulating ,2 -adrenoreceptors. A total of 47 male Sprague,Dawley rats weighing 330,450 g were used in a prospective, randomized, controlled in vitro study. Following animal anaesthetization, diaphragms were excised, and muscle strips prepared and placed in a temperature-controlled isolated tissue bath containing Krebs,Ringer solution (KR) or KR plus 100 ,m DA. The solutions were equilibrated with oxygen (O2) at 10, 21 or 95% and 5% carbon dioxide, with the balance being nitrogen. Diaphragm isometric twitch and subtetanic contractions were measured intermittently over 65 min. The diaphragms were then removed and, using a nuclear differential dye uptake method, the percentages of normal, apoptotic and necrotic nuclei were determined using fluorescent microscopy. There were significantly fewer apoptotic nuclei in the DA group diaphragms than in the KR-only group diaphragms in 10 and 21% O2 following either twitch or subtetanic contractions. Dopamine at 100 ,m produced only modest increases in muscle performance in both 10 and 21% O2. The attenuation of apoptosis by DA was markedly greater than the effect of DA on muscle performance. Dopamine decreased diaphragmatic apoptosis, perhaps by preventing the activation of intricate apoptotic pathways, stimulating antiapoptotic mechanisms and/or scavenging free radicals. [source]

Inhibition of carbachol-evoked oscillatory currents by the NO donor sodium nitroprusside in guinea-pig ileal myocytes

EXPERIMENTAL PHYSIOLOGY, Issue 4 2005
Seung-Soo Chung
The effect of sodium nitroprusside (SNP) on carbachol (CCh)-evoked inward cationic current (Icat) oscillations in guinea-pig ileal longitudinal myocytes was investigated using the whole-cell patch-clamp technique and permeabilized longitudinal muscle strips. SNP (10 ,m) completely inhibited Icat oscillations evoked by 1 ,m CCh. 1H-(1,2,4) Oxadiazole [4,3-a] quinoxaline-1-one (ODQ; 1 ,m) almost completely prevented the inhibitory effect of SNP on Icat oscillations. 8-Bromo-guanosine 3,,5,-cyclic monophosphate (8-Br-cGMP; 30 ,m) in the pipette solution completely abolished Icat oscillations. However, a pipette solution containing Rp-8-Br-cGMP (30 ,m) almost completely abolished the inhibitory effect of SNP on Icat oscillations. When the intracellular calcium concentration ([Ca2+]i) was held at a resting level using BAPTA (10 mm) and Ca2+ (4.6 ,m) in the pipette solution, CCh (1 ,m) evoked only the sustained component of Icat without any oscillations and SNP did not affect the current. A high concentration of inositol 1,4,5-trisphosphate (IP3; 30 ,m) in the patch pipette solutions significantly reduced the inhibitory effect of SNP (10 ,m) on Icat oscillations. SNP significantly inhibited the Ca2+ release evoked by either CCh or IP3 but not by caffeine in permeabilized preparations of longitudinal muscle strips. These results suggest that the inhibitory effects of SNP on Icat oscillations are mediated, in part, by functional modulation of the IP3 receptor, and not by the inhibition of cationic channels themselves or by muscarinic receptors in the plasma membrane. This inhibition seems to be mediated by an increased cGMP concentration in a protein kinase G-dependent manner. [source]

Effect of human chorionic gonadotrophin on in vitro contractions of stimulated detrusor muscle strips of female rats

Ethanol Upregulates iNOS Expression in Colon Through Activation of Nuclear Factor-kappa B in Rats

ALCOHOLISM, Issue 1 2010
Chao Wang
Background:, Alcohol inhibits colonic motility but the mechanism is unknown. The goal of this study was to test the possibility that nuclear factor-kappa B (NF-,B) is involved in the upregulation of inducible nitric oxide synthase (iNOS) expression induced by ethanol in colon. Methods:, The isometric contraction of longitudinal muscle strips of proximal colon (LP) was monitored by polygraph. Western blot analysis was used to measure the amount of iNOS and I-,B in the cytoplasm and P65 in the nucleus. Immunohistochemistry was applied to locate iNOS in colon. Results:, Ethanol (87mM) inhibited the contraction of LP. Pretreatment of S-methylisothioure (SMT) (1 mM), a specific iNOS inhibitor, Pyrrolidine dithiocarbamate (PDTC) (10 mM) and BAY11-7082(10 mM), specific inhibitors of NF-,B significantly reversed the inhibitory effect of ethanol on LP contraction. Ethanol increased the amount of iNOS and content of NO in colon, and these effects were attenuated by pretreatment of PDTC. Following ethanol administration, the amount of I-,B in the cytoplasm decreased, but that of P65, the subunit of NF-,B in the nucleus, increased. The iNOS was located in the cell body of myenteric plexus in colon. Conclusion:, Ethanol inhibited the contraction of LP in colon mainly through activation of NF-,B, the subsequent upregulation of iNOS expression and increase of NO release in myenteric plexus. [source]

Cell-free supernatants of Escherichia coli Nissle 1917 modulate human colonic motility: evidence from an in vitro organ bath study

NEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2009
F. 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]

Oxytocin receptor expressed on the smooth muscle mediates the excitatory effect of oxytocin on gastric motility in rats

NEUROGASTROENTEROLOGY & MOTILITY, Issue 4 2009
J. Qin
Abstract, The aim of this study was to localize oxytocin receptor (OTR) in the stomach and to investigate the effect of OT on gastric motility in rats. Western blot and immunohistochemistry methods were used to localize OTR in stomach. The motility of stomach was recorded in vivo (recording of the intragastric pressure), in vitro (recording of the contraction of muscle strips) and on isolated smooth muscle cells. OTR was expressed on cells of both circular and longitudinal muscle of stomach. Systemic administration of OT induced an early transient decrease and a subsequent increase on intragastric pressure. Devazepide (1 mg kg,1, i.v.), a cholecystokinin-1 (CCK1) receptor antagonist, completely abolished the transient response but did not influence the subsequent one. OT (10,9,10,6 mol L,1) dose-dependently increased the contraction of the muscle strips of gastric body, antrum, and pyloric sphincter, and decreased the average cell length of isolated smooth muscle cells. Tetrodotoxin and atropine did not influence the effect of OT on muscle strips. Pretreatment with atosiban, an OTR antagonist, inhibited the spontaneous contraction of muscle strips and abolished the excitatory effect of OT on the muscle strips and the isolated cells. These results suggest that the OTR is expressed on the smooth muscle of the stomach and mediates excitatory effect of OT on gastric motility. [source]

Endogenous and exogenous ghrelin enhance the colonic and gastric manifestations of dextran sodium sulphate-induced colitis in mice

NEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2009
B. De Smet
Abstract, Ghrelin is an important orexigenic peptide that not only exerts gastroprokinetic but also immunoregulatory effects. This study aimed to assess the role of endogenous and exogenous ghrelin in the pathogenesis of colitis and in the disturbances of gastric emptying and colonic contractility during this process. Dextran sodium sulphate colitis was induced for 5 days in (i) ghrelin+/+ and ghrelin,/, mice and clinical and histological parameters were monitored at days 5, 10 and 26 and (ii) in Naval Medical Research Institute non-inbred Swiss (NMRI) mice treated with ghrelin (100 nmol kg,1) twice daily for 5 or 10 days. Neural contractility changes were measured in colonic smooth muscle strips, whereas gastric emptying was measured with the 14C octanoic acid breath test. Inflammation increased ghrelin plasma levels. Body weight loss, histological damage, myeloperoxidase activity and IL-1, levels were attenuated in ghrelin,/, mice. Whereas absence of ghrelin did not affect changes in colonic contractility, gastric emptying in the acute phase was accelerated in ghrelin+/+ but not in ghrelin,/, mice. In agreement with the studies in ghrelin knockout mice, 10 days treatment of NMRI mice with exogenous ghrelin enhanced the clinical disease activity and promoted infiltration of neutrophils and colonic IL-1, levels. Unexpectedly, ghrelin treatment decreased excitatory and inhibitory neural responses in the colon of healthy but not of inflamed NMRI mice. Endogenous ghrelin enhances the course of the inflammatory process and is involved in the disturbances of gastric emptying associated with colitis. Treatment with exogenous ghrelin aggravates colitis, thereby limiting the potential therapeutic properties of ghrelin during intestinal inflammation. [source]

Effects of extrinsic denervation on innervation with VIP and substance P in circular muscle of rat jejunum,

Nitric oxide mediates the inhibitory effect of ethanol on the motility of isolated longitudinal muscle of proximal colon in rats

NEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2007
S. 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]

Fibre-free diet leads to impairment of neuronally mediated muscle contractile response in rat distal colon

NEUROGASTROENTEROLOGY & MOTILITY, Issue 12 2006
R. Mitsui
Abstract, Dietary fibre consumption is known to be beneficial to increase stool bulk and frequency. In contrast, it is unclear whether chronic dietary fibre deficiency affects colonic motor functions, especially neuronally mediated muscle contractions. In this study, rats were fed a fibre-free diet or diet containing dietary fibre (cellulose or guar gum) for 27 days. Furthermore, neurogenic and myogenic contractions were evaluated in circular and longitudinal muscle strips of the distal colon. Additionally, the number of enterochromaffin (EC) cells, which play important roles in the initiation of the peristaltic reflex, was also examined by immunohistochemistry for serotonin. Myogenic contractions induced by carbachol or substance P were examined in the presence of tetrodotoxin. Circular muscle was hyposensitive to carbachol, but longitudinal muscle was hypersensitive to substance P in the fibre-free group. Nerve-mediated circular (5,20 Hz) and longitudinal (1,2 Hz) muscle contractions evoked by electrical field stimulation were attenuated in the fibre-free group and the latter response was almost abolished by atropine, suggesting functional changes of cholinergic neurons. EC cell number was decreased in the fibre-free group. In conclusion, changes in neurogenic and myogenic contractions and a decrease in EC cell number observed may affect colonic motility of the fibre-free group. [source]

The herbal preparation STW5 (lberogast®) has potent and region-specific effects on gastric motility

Nitrergic,purinergic interactions in rat distal colon motility

NEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2004
K. Van Crombruggen
Abstract, Responses of rat distal colon circular muscle strips to exogenous nitric oxide (NO) and adenosine 5,-triphosphate (ATP) and to electrical field stimulation (EFS) were assessed in the absence/presence of various agents that interfere with nitrergic,purinergic pathways. Exogenous NO (10,6 to 10,4 mol L,1) elicited concentration-dependent, tetrodotoxin (TTX)-insensitive relaxations. The soluble guanylyl-cyclase (sGC) inhibitor 1H[1,2,4,]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) reduced duration and amplitude; the small conductance Ca2+ -sensitive K+ (SK)-channel blocker apamin (APA) only shortened the relaxations. ODQ + APA showed a marked inhibitory effect on duration and amplitude. TTX, APA, the NO-synthase inhibitor N(omega)-nitro- l -arginine methyl ester (l -NAME) and the purinergic receptor P2Y antagonist Reactive Blue 2 (RB2) shortened the relaxations by exogenous ATP (10,3 mol L,1) but did not influence the amplitude. ODQ had no effect. TTX + l -NAME did not yield a more pronounced inhibitory effect than TTX alone. The effect of ATP- , -S was similar to that of ATP. Electrical field stimulation (EFS) (40 V, 0.05 ms, 0.5,4 Hz for 30 s) yielded TTX-sensitive relaxations that were not altered by l -NAME, ODQ or RB2. APA shortened the relaxations. l -NAME + APA nearly abolished these relaxations. ODQ + APA and RB2 +l -NAME reduced the duration. These results suggest that distinct sets of small conductance SK-channels are involved in the amplitude and the duration of the relaxations and that NO increases their sensitivity to NO and ATP via guanosine 3,,5,-cyclic monophosphate (cGMP). ATP elicits relaxations via P2Y receptors with subsequent activation of SK-channels and induces neuronal release of NO. Both nitrergic and purinergic pathways must be blocked to inhibit EFS-induced relaxations. [source]

Effect of endotoxin on opossum oesophageal motor function

NEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2000
H. Park
Endotoxin induces nitric oxide (NO,) synthase and alters gastrointestinal functions. We explored the effect of lipopolysaccharide (LPS) on oesophageal motor function at 6, 12, 24, and 48 h. The effects of inhibiting inducible NO, synthase (iNOS) were studied 12 h after administration of LPS with/without aminoguanidine (AG). Oesophageal manometry was performed and tissue bath studies were performed with muscle strips from the oesophagus and lower oesophageal sphincter (LOS). Plasma nitrite/nitrate concentrations were determined. The amplitudes of peristaltic pressure waves, resting LOS pressure and the percentage LOS relaxations were diminished by LPS. AG attenuated the decrease in amplitude of oesophageal pressure waves, LOS pressure, and percentage relaxation of LOS brought about by LPS. LPS decreased electrical field stimulation (EFS)-induced relaxation of LOS muscle. AG attenuated this decrease in LOS relaxation. The off-response of transverse oesophageal muscle strips was decreased, and AG antagonized this effect. Plasma concentrations of nitrite/nitrate were increased. The increase in plasma nitrite/nitrate was attenuated by AG. These studies support the hypothesis that endotoxin modulates oesophageal motor function by increasing NO production and suggest that this results from the induction of iNOS. [source]

Effects of imatinib mesylate (Glivec®) as a c-kit tyrosine kinase inhibitor in the guinea-pig urinary bladder

NEUROUROLOGY AND URODYNAMICS, Issue 3 2006
Yasue Kubota
Abstract Aims In the gastrointestinal tract, slow wave activity in smooth muscle is generated by the interstitial cells of Cajal (ICC). Detrusor smooth muscle strips of most species show spontaneous contractions which are triggered by action potential bursts, however, the pacemaker mechanisms for the detrusor are still unknown. Recently, ICC-like cells have been found in guinea-pig bladder, using antibodies to the c-kit receptor. We have investigated the effects of Glivec, a c-kit tyrosine kinase inhibitor, on spontaneous action potentials in guinea-pig detrusor and intravesical pressure of isolated guinea-pig bladders. Methods Changes in the membrane potential were measured in guinea-pig detrusor smooth muscle using conventional microelectrode techniques. Pressure changes in the bladder were recorded using whole organ bath techniques. Results Smooth muscle cells in detrusor muscle bundles exhibited spontaneous action potentials, and spontaneous pressure rises occurred in isolated bladders. Glivec (10 ,M) converted action potential bursts into continuous firing with no effects on the shape of individual action potentials. Glivec (>50 ,M) reduced the amplitude of spontaneous pressure rises in the whole bladder in a dose dependent manner and abolished spontaneous action potentials in detrusor smooth muscle cells. Conclusions The results suggest that ICC-like cells may be responsible for generating bursts of action potentials and contractions in detrusor smooth muscle. Drugs inhibiting the c-kit receptor may prove useful for treating the overactive bladder. Neurourol. Urodynam. © 2006 Wiley-Liss, Inc. [source]

Preconditioning protects the guinea-pig urinary bladder against ischaemic conditions in vitro

NEUROUROLOGY AND URODYNAMICS, Issue 7 2003
Bruno 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]

Proteomic profiling and identification of cofilin responding to oxidative stress in vascular smooth muscle

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 24 2006
Chang-Kwon Lee
Abstract We used 2-DE and MALDI-TOF/TOF to identify proteins of vascular smooth muscle cells whose expression was or was not altered by exposure to 500,,M H2O2 for 30,min. We detected more than 800 proteins on silver-stained gels of whole protein extracts from rat aortic smooth muscle strips. Of these proteins, 135 clearly unaffected and 19 having levels altered by exposure to H2O2 were identified. Protein characterization revealed that the most prominent vascular smooth muscle proteins were those with antioxidant, cytoskeletal structure, or muscle contraction. In addition, cofilin, an isoform of the actin depolymerizing factor family, shifted to its basic site on the 2-DE gel as a result of H2O2 treatment. In Western blot analysis of proteins from A7r5 aortic smooth muscle cells, the phosphorylation, but not the expression, of cofilin was decreased by H2O2 in a dose-dependent manner. The H2O2 -induced dephosphorylation of cofilin and apoptosis was inhibited by Na3VO4, an inhibitor of protein tyrosine phosphatase (PTP). These results suggest that cofilin is one of the proteins regulated by H2O2 treatment in vascular smooth muscle, and has an important role in the induction of vascular apoptosis through PTP-dependent mechanisms. [source]

AMP kinase activation with AICAR further increases fatty acid oxidation and blunts triacylglycerol hydrolysis in contracting rat soleus muscle

Alpha1A/L -adrenoceptors mediate contraction of the circular smooth muscle of the pig urethra

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 4 2006
K. Bagot
Summary 1 Sympathetically mediated urethral tone is essential for the maintenance of continence and involves the activation of postjunctional ,1 -adrenoceptors. This study characterizes the ,1 -adrenoceptor subtypes responsible for mediating contraction of the urethral circular smooth muscle of the pig. 2 The potency order of a number of agonists and the affinities of several receptor selective antagonists were determined on pig-isolated circular smooth muscle strips in the presence of cocaine (1 ,m) and corticosterone (10 ,m) to inhibit amine uptake and propranolol (1 ,m) to antagonize , -adrenoceptors. 3 The potency order for agonists was N -[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A61603) > noradrenaline = phenylephrine = M6434 > methoxamine with pEC50 values of 7.3, 5.8, 5.7, 5.6 and 5.0 respectively. 4 The ,1D -adrenoceptor-selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione (BMY7378) caused rightward shifts of the concentration,response curves to noradrenaline, yielding a low affinity estimate (6.6) for the urethral receptor. The ,1A -adrenoceptor-selective antagonists, RS100329 and 5-methylurapidil, gave relatively high affinity estimates (9.6 and 8.8 respectively) for this receptor. All three antagonists produced Schild plots with slopes close to unity but did reduce maximum responses at higher concentrations. Prazosin antagonized responses of the urethra to noradrenaline, yielding a mean affinity estimate of 9.0. Although the Schild plot for prazosin again had a slope of unity, this drug also reduced maximum responses to noradrenaline at all concentrations examined (10,100 nm). N -[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro- ,,, -dimethyl-1H-indole-3-ethanamide (RS17053), which discriminates between responses mediated via ,1A (high affinity) and ,1L -adrenoceptors (low affinity) at concentrations up to 3 ,m, failed to antagonize responses of the urethra. 5 These results suggest that contraction of urethral circular smooth muscle in the pig is mediated via a single population of adrenoceptors with the pharmacological characteristics of the ,1A/L -adrenoceptor, most probably the ,1L -adrenoceptor. [source]

Emodin Inhibits Voltage-Dependent Potassium Current in Guinea Pig Gallbladder Smooth Muscle

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2009
Zhi-Xuan Wu
We studied the effects of emodin on the contraction of gallbladder smooth muscle and voltage-dependent K+ current in gallbladder smooth muscle cells. Gallbladder muscle strips were obtained from adult guinea pigs and the resting tension was recorded. Gallbladder smooth muscle cells were isolated by enzymatic digestion, and K+ current was recorded by the whole-cell patch clamp method. Emodin increased the resting tension of gallbladder smooth muscle strips and inhibited voltage-dependent K+ current in a dose-dependent manner. When 10 µM emodin was applied to gallbladder smooth muscle cells for 3,6 min., the amplitude of voltage-dependent K+ current was decreased by 31.5 ± 0.5% at +40 mV, and this inhibitory effect mostly recovered after washout. The steady-state inactivation curves were shifted in a hyperpolarizing direction by emodin. In the presence of the protein kinase C inhibitors staurosporine and chelerythrine, the effect of emodin on voltage-dependent K+ current was significantly attenuated. In conclusion, emodin promotes gallbladder contraction, mainly by inhibiting voltage-dependent K+ current via the protein kinase C pathway. These findings provide theoretical foundation for the application of emodin in gallbladder motility disorders. [source]

Lack of effectiveness of botulinum neurotoxin A on isolated detrusor strips and whole bladders from mice and guinea-pigs in vitro

BJU INTERNATIONAL, Issue 10 2009
Sarah Howles
OBJECTIVE To differentiate between the effects of parasympathetic and sensorimotor stimulation of isolated mouse and guinea-pig bladders in vitro by measuring the pressure increases to electrical field stimulation (EFS) and then comparing the effects of botulinum neurotoxin A (BoNT-A) applied either to the lumen or to the external bathing medium. MATERIALS AND METHODS Isolated mouse and guinea-pig bladders and detrusor strips were exposed to EFS in vitro before and after the addition of BoNT-A. The rationale of this method was that BoNT-A applied to the outside of the bladder would first affect the parasympathetic nerves before diffusing inwards to affect the sensorimotor innervation. BoNT-A applied intravesically would first reach the sensorimotor nerves and only later the parasympathetic nerves. Initial experiments on strips of detrusor were conducted to establish the correct dosage and application time of BoNT-A. RESULTS Contrary to our expectations, BoNT-A application failed to produce any significant effects on either the detrusor strips or whole bladders. CONCLUSIONS Our experimental design failed to show any effect of BoNT-A on the contractility of detrusor muscle strips or whole bladders from mice and guinea-pigs. The reason for this is unclear, but may be related to tissue spending inadequate time incubated with BoNT-A under physiological conditions. [source]

Effect of letrozole on urinary bladder function in the female rabbit

BJU INTERNATIONAL, Issue 6 2007
Wei-Yu Lin
OBJECTIVE To investigate the effect of letrozole (a potent aromatase inhibitor that effectively inhibit the synthesis of oestrogen) on bladder contraction with changes in morphology and biochemistry. MATERIALS AND METHODS Sixteen female New Zealand white rabbits were separated into four equal groups; groups 1,3 were given oral letrozole for 1, 2 and 3 weeks, and group 4 was given saline and served as the control group. At the end of the medication period each rabbit was anaesthetized and the bladder muscle strips were used for contractile, histological and biochemical studies. RESULTS The concentration of serum oestrogen was significantly lower and testosterone was significantly higher in letrozole-treated rabbits than in the control group. The rabbits treated for 1 week with letrozole showed significant decreases in the contractile responses to electrical field stimulation, ATP and carbachol, but not to KCl. Contractility returned to normal in the rabbits treated for 2 and 3 weeks. Letrozole resulted in an increased volume percentage of collagens and decreased bladder compliance. The volume percentage of the smooth muscle component also changed, with a significant decrease at 1 week and then a gradual increase at 2 and 3 weeks. Contractile dysfunction was absent at 2 and 3 weeks, which was consistent with no change in sarcoplasmic reticulum Ca2+ -ATPase content or mitochondrial function. CONCLUSIONS The bladder contractility decline in the first week and was restored at 2 and 3 weeks. The present study unexpectedly showed the possibility that testosterone might be as important as oestrogen in the contractile function of the female bladder. [source]

An evaluation of laparoscopic tissue harvesting for human adult urological smooth muscle physiological experimentation

Continence and some properties of the urethral striated muscle of male greyhounds

BJU INTERNATIONAL, Issue 3 2000
B.A. Van Der Werf
Objective To determine the properties of the striated muscle of the greyhound (dog) urethra and to consider its role in maintaining continence. Materials and methods The thickness of the muscle layers and the muscle types were determined by examining sections stained with haematoxylin and eosin or Masson's trichrome. These factors were correlated with the mechanical and electrical responses of muscle strips to nerve stimulation, and compared with muscle from other breeds of dog and other parts of the animal. Results The striated muscle formed ,70% of the membranous urethra and was predominantly (68%) type IIa muscle (i.e. fast but fatigue-resistant). The mean resting membrane potential was ,74 mV; nerve stimulation produced an action potential with a mean amplitude of 97 mV and contraction lasting about 200 ms. All responses were abolished by d -tubocurarine. The contractions were well maintained with continuous or intermittent stimulation. The properties were intermediate between those of the anconeus (slow) and the extensor carpi radialis (fast) muscles. Conclusions The distribution, fibre type and contractile characteristics would enable the striated urethral muscle to maintain tension for continence at rest and provide additional continence during sprints. [source]