			Home About us Contact

Krebs' Solution (Kreb + solution)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

The neuronal and endothelium-dependent relaxing responses of human corpus cavernosum under physiological oxygen tension last longer than previously expected

INTERNATIONAL JOURNAL OF UROLOGY, Issue 5 2004
KAZUNORI 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]

Oesophageal morphometry and residual strain in a mouse model of osteogenesis imperfecta

NEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2001
H. Gregersen
Recently, it was demonstrated in the oesophagus that the zero-stress state is not a closed cylinder but an open circular cylindrical sector. The closed cylinder with no external loads applied is called the no-load state and residual strain is the difference in strain between the no-load state and the zero-stress state. To understand the physiology and pathology of the oesophagus, it is necessary to know the zero-stress state and the stress,strain relationships of the tissues in the oesophagus, and the changes of these states and relationships due to biological remodelling of the tissues under stress. The aim of this study was to investigate the morphological and biomechanical remodelling at the no-load and zero-stress states in mutant osteogenesis imperfecta murine (oim) mice with collagen deficiency. The oesophagi of seven oim and seven normal wild-type mice were excised, cleaned, and sectioned into rings in an organ bath containing calcium-free Krebs solution with dextran and EGTA. The rings were photographed in the no-load state and cut radially to obtain the zero-stress state. Equilibrium was awaited for 30 min and the specimens were photographed again. Circumferences, submucosa and muscle layer thicknesses and areas, and the opening angle were measured from the digitized images. The oesophagi in oim mice had smaller layer thicknesses and areas compared to the wild types. The largest reduction in layer thickness in oim mice was found in the submucosa (approximately 36%). Oim mice had significantly larger opening angles (120.2 ± 4.5°) than wild-type mice (93.0 ± 11.2°). The residual strain was compressive at the mucosal surface and tensile at the serosal surface in both oim and wild types. In the oim mice, the residual strains at the serosal and mucosal surfaces and the mucosa-submucosal,muscle layer interface were higher than in the wild types (P < 0.05). The gradient of residual strain per unit thickness was higher in oim mice than in wild-type mice, and was highest in submucosa (P < 0.05). The only morphometric measure that was similar in oim and wild-type mice was the inner circumference in the no-load state. In conclusion, our data show significant differences in the residual strain distribution and morphometry between oim mice and wild-type mice. The data suggest that the residual stress in oesophagus is caused by the tension in the muscle layer rather than the stiffness of the submucosa in compression and that the remodelling process in the oim oesophagus is due mainly to morphometric and biomechanical alterations in the submucosa. [source]

Excitatory purinergic neurotransmission in smooth muscle of guniea-pig taenia caeci

THE JOURNAL OF PHYSIOLOGY, Issue 3 2005
Yong Zhang
Non-adrenergic, non-cholinergic (NANC) inhibitory neurotransmission has been an area of intense interest in gut motor physiology, whereas excitatory NANC neurotransmission has received less attention. In order to further explore excitatory NANC neurotransmission, we performed conventional intracellular recordings from guinea-pig taenia caeci smooth muscle. Tissue was perfused with oxygenated Krebs solution at 35°C and nerve responses evoked by either oral or aboral nerve stimulation (NS) (4 square wave pulses, 0.3 ms duration, 20 Hz). Electrical activity was characterized by slow waves upon which one to three action potentials were superimposed. Oral NS evoked an inhibitory junction potential (IJP) at either the valley or peak of the slow wave. Application of nifedipine (1 ,m) abolished slow waves and action potentials, but membrane potential flunctuations (1,3 mV) and IJPs remained unaffected. Concomitant application of apamin (300 nm), a small-conductance Ca2+ -activated K+ channel blocker, converted the IJP to an EJP that was followed by slow IJP. Further administration of NG -nitro- l -arginine methyl ester (l -NAME, 200 ,m), a nitric oxide synthase inhibitor, abolished the slow IJP without affecting the EJP, implying that the slow IJP is due to nitrergic innervation. The EJP was abolished by tetrodotoxin (1 ,m), but was not significantly affected by atropine (3 ,m) and guanethidine (3 ,m) or hexamethonium (500 ,m). Substance P (SP, 1 ,m) desensitization caused slight attenuation of the EJP, but the EJP was abolished by desensitization with ,,,-methylene ATP (50 ,m), a P2 purinoceptor agonist that is more potent than ATP at the P2X receptor subtype, suramin (100 ,m), a non-selective P2 purinoceptor antagonist, and pyridoxal-phosphate-6-azophenyl-2,,4,-disulphonic acid (PPADS, 100 ,m), a selective P2X purinoceptor antagonist. In contrast, the EJP was unaffected by MRS-2179 (2 ,m), a selective P2Y1 receptor antagonist. Aboral NS evoked an apamin- and l -NAME-sensitive IJP, but virtually no NANC EJP. These data suggest the presence of polarized excitatory purinergic neurotransmission in guinea-pig taenia caeci, which appears to be mediated by P2X purinoceptors, most likely the P2X1 subtype. [source]

A rapid and simple method for determination of halothane, iso,urane and sevo,urane in blood using gas chromatography

BIOMEDICAL CHROMATOGRAPHY, Issue 9 2004
Richard J. Atherley
Abstract We have developed a technique to determine the concentration of volatile anesthetics (halothane, iso,urane and sevo,urane) in blood that is a modi,cation of a method used for volatile anesthetics in Krebs solution. Methylene chloride was the internal standard and chloroform was used to extract the volatile anesthetic from blood. The congealed blood proteins were separated from the chloroform solvent (containing anesthetic) using a two-compartment vial that ,ltered out the proteinaceous material during centrifuging. Recovery averaged 102%. Linearity was excellent (r = 0.992,0.999) in the 50,600, 50,300 and 50,300 µg/mL range for halothane, iso,urane and sevo,urane, respectively. Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <5.3 and <7.1%, respectively. Accuracy ranged from 0.8 to 9.5% of the estimated theoretical value. Extracted anesthetic in chloroform solvent was stable over 4,5 days, with <3% variability. The time from obtaining the blood sample to determination of the concentration from the chromatographic peak was 15 min or less. Copyright © 2004 John Wiley & Sons, Ltd. [source]

The neuronal and endothelium-dependent relaxing responses of human corpus cavernosum under physiological oxygen tension last longer than previously expected

Impaired EDHF-Mediated Relaxation in Porcine Pulmonary Micro-Arteries by Cold Storage with University of Wisconsin and Euro-Collins Solutions

JOURNAL OF CARDIAC SURGERY, Issue 6 2002
Wei Zou
Background: Vascular endothelium plays a key role in regulation of vascular tone. Hyperkalemia has been demonstrated to impair the EDHF-mediated endothelial function in coronary circulation. University of Wisconsin (UW) and Eruo-collins (EC) solutions are used for organ preservation in transplantation surgery. The potassium concentration in UW or EC solutions is as high as 125 mmol/L or 115 mmol/L, respectively. This study was designed to examine whether hyperkalemia or storage with UW and EC solutions affects the relaxation mediated by EDHF in the porcine pulmonary micro-arteries. Methods: Porcine pulmonary micro-artery rings (diameter 200,450 ,m) were studied in myograph (n = 8 in each group). After incubation with hyperkalemia (K+ 125 mmol/L, at 37° C), UW or EC solutions (at 4° C for 4 hours), EDHF-mediated relaxation induced by bradykinin (BK, ,10 to ,6.5 log M) in the presence of inhibitors for cyclooxygenase (Indomethacin, 7 ,M), nitric oxide synthase (NG -nitro- L -arginine, 300 ,M), and oxyhemoglobin (20 ,M) was compared with control (Krebs' solution) in precontraction with U46619 (,7.5 log M). Results: The EDHF-mediated relaxation to BK was 69.6 ± 6.3% compared with 97.1 ± 1.7% (p= 0.003) in control (no inhibitors). After incubation with hyperkalemia, the relaxation significantly decreased (38.6 ± 3.0% vs. 59.1 ± 7.4%, p= 0.03). Storage with UW or EC solutions also significantly decreased the relaxation (49.3 ± 7.3% vs. 65.2 ± 3.5%, p= 0.04 and 51.9 ± 8.4% vs. 60.3 ± 6.1%, p= 0.02, respectively). Conclusions: In porcine pulmonary micro-arteries, exposure to hyperkalemia or storage with UW or EC solutions at 4°C for 4 hours impairs the EDHF-mediated endothelial function. The clinical significance of this effect should be further studied. [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]

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]

2124: Src family tyrosine kinase activation is required for endothelin-1 to inhibit Na,K-ATPase in porcine lens epithelium

ACTA OPHTHALMOLOGICA, Issue 2010
NA DELAMERE
Purpose Earlier studies point to the involvement of Src family tyrosine kinases (SFKs) in the stimulation of of Na,K-ATPase activity by purinergic receptor agonists ATP and UTP. Src itself was activated (Tamiya, et al. 2007, Am. J. Physiol. 293: C790-6). Here, we examined the role of SFKs in the response to endothelin-1 (ET-1), an ET receptor agonist that causes Na,K-ATPase inhibition. Methods Porcine lenses were incubated 30 min in Krebs' solution with ET-1 or other test agents. The epithelium was removed, homogenized and analyzed by western blot or Na,K-ATPase activity assay. Results Exposure of the intact lens to ET-1 caused a reduction in Na,K-ATPase activity. The Na,K-ATPase response was not observed when lenses were pretreated with 10 uM PP2, a selective inhibitor of SFKs. ET-1 caused SFK activation evident from an increase in Y416 phosphorylation and decrease in Y527 phosphorylation of a ~61kDa SFK. The SFK inhibitor PP2 abolished the SFK phosphorylation response. Since SFKs Fyn, Src, Hck and Yes may contribute to the observed 61kDa band, these SFKs were isolated by immunoprecipitation and analyzed separately. Based on Y416 phosphorylation, ET-1 appeared to activate Fyn, while Src and Hck were inhibited. Yes activity was unaltered. Conclusion ET-1, which causes Na,K-ATPase inhibition, elicits a different pattern of SFK activation from that reported earlier for purinergic agonists which stimulate Na,K-ATPase activity. Previously, Na,K-ATPase stimulation was observed when Src was activated. The ET-1 response points to Na,K-ATPase inhibition when Fyn kinase is activated. [source]

A ROLE FOR RHO-KINASE IN Ca2+ -INDEPENDENT CONTRACTIONS INDUCED BY PHORBOL-12,13-DIBUTYRATE

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2009
Inji Baek
SUMMARY 1Phorbol-12,13-dibutyrate (PDBu) is an activator of protein kinase C (PKC) that causes contractions in both physiological salt solutions and Ca2+ -depleted solutions. In the present study, we tested the hypothesis that Rho-kinase plays a role in Ca2+ -independent contractions induced by PDBu in vascular smooth muscles. 2In Ca2+ -free solution, 0.1 and 1 µmol/L PDBu induced contraction and myosin light chain (MLC20) phosphorylation, both of which were approximately 40% of responses obtained in normal Krebs' solution. Hydroxyfasudil (H1152; 1 µmol/L), an inhibitor of Rho-kinase, but not ML7 (10 µmol/L), an inhibitor of myosin light chain kinase, inhibited Ca2+ -independent contractions induced by PDBu. 3In Ca2+ -free solution, PDBu increased phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and CPI-17 (PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa). This action was inhibited by H1152, with the phosphorylation of CPI-17 almost completely abolished by 1 µmol/L Ro31-8220, an inhibitor of PKC. 4In Ca2+ -free solution, PDBu increased the amount of GTP-RhoA (an activated form of RhoA). This increase was blocked by the PKC inhibitor Ro31-8220, but not by the Rho kinase inhibitor H1152. 5In conclusion, RhoA/Rho-kinase plays an important role in Ca2+ -independent contractions induced by PDBu in vascular smooth muscles. The results of the present study suggest that PDBu induces Ca2+ -independent contractions by inhibiting myosin light chain phospatase (MLCP) through activation of GTP-RhoA and subsequent phosphorylation of MYPT1 and CPI-17. [source]