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Henseleit Buffer (henseleit + buffer)
Selected AbstractsQuantification of myoglobin deoxygenation and intracellular partial pressure of O2 during muscle contraction during haemoglobin-free medium perfusionEXPERIMENTAL PHYSIOLOGY, Issue 5 2010Hisashi Takakura Although the O2 gradient regulates O2 flux from the capillary into the myocyte to meet the energy demands of contracting muscle, intracellular O2 dynamics during muscle contraction remain unclear. Our hindlimb perfusion model allows the determination of intracellular myoglobin (Mb) saturation () and intracellular oxygen tension of myoglobin () in contracting muscle using near infrared spectroscopy (NIRS). The hindlimb of male Wistar rats was perfused from the abdominal aorta with a well-oxygenated haemoglobin-free Krebs,Henseleit buffer. The deoxygenated Mb (,[deoxy-Mb]) signal was monitored by NIRS. Based on the value of ,[deoxy-Mb],,,and,,were calculated, and the time course was evaluated by an exponential function model. Both,,and,,started to decrease immediately after the onset of contraction. The steady-state values of,,and,,progressively decreased with relative work intensity or muscle oxygen consumption. At the maximal twitch rate,,,and,,were 49% and 2.4 mmHg, respectively. Moreover, the rate of release of O2 from Mb at the onset of contraction increased with muscle oxygen consumption. These results suggest that at the onset of muscle contraction, Mb supplies O2 during the steep decline in,, which expands the O2 gradient to increase the O2 flux to meet the increased energy demands. [source] Inhibition of TXA2 synthesis with OKY-046 improves liver preservation by prolonged hypothermic machine perfusion in ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7pt2 2008Hongzhi Xu Abstract Background and Aim:, We previously reported that hypothermic machine perfusion (HMP) for liver preservation is feasible, but hepatic microcirculatory dysfunction and significant liver damage remain major obstacles in its application when the preservation is extended to 24 h. The underlying injury mechanism is not well understood. The present study sought to investigate the role of thromboxane A2 (TXA2) in the pathogenesis of liver injury after prolonged HMP. Methods:, Livers isolated from Sprague,Dawley rats were subjected to continuous machine perfusion with University of Wisconsin (UW) solution at a flow rate of 0.4 mL/min/g liver at 4°C for 24 h. A specific TXA2 synthase inhibitor, OKY-046 (OKY), was added to UW solution during the preservation period and to the Krebs,Henseleit buffer during reperfusion. The performance of the livers after preservation was evaluated using an isolated liver perfusion system with Krebs,Henseleit buffer at a flow rate of 15 mL/min at 37°C for 30 min. Results:, Prolonged HMP induced a significant release of TXA2 into the portal circulation as indicated by markedly increased levels of TXB2 in the perfusate during reperfusion (at 30 min, 1447.4 ± 163.6 pg/mL vs 50.91 ± 6.7 pg/mL for control). Inhibition of TXA2 synthesis with OKY significantly decreased releases of TXA2 (69.8 ± 13.4 pg/mL) concomitant with reduced lactate dehydrogenase (LDH) releases (at 30 min, HMP + OKY: 144.9 ± 27.9 U/L; HMP: 369.3 ± 68.5 U/L; simple cold storage or SCS: 884.4 ± 80.3 U/L), decreased liver wet/dry weight ratio (HMP + OKY vs SCS and HMP: 3.6 ± 0.3 vs 4.4 ± 0.1 and 3.9 ± 0.2, respectively) and increased hyaluronic acid uptake (at 30 min, HMP + OKY vs SCS, HMP: 33.1 ± 2.9% vs 13.9 ± 3.6%, 18.6 ± 2.4%, respectively). Liver histology also showed significant improvement in tissue edema and hepatocellular necrosis with OKY compared with HMP without OKY. Conclusion:, The results demonstrate that TXA2 is involved in the development of hepatocellular injury induced by HMP, and inhibition of TXA2 synthesis during preservation and reperfusion protects liver hepatocytes and sinusoidal endothelial cells from injuries caused by prolonged HMP. [source] Portal hypertensive response to bradykinin in inflamed or cirrhotic rat livers is mediated by B2 -type receptorsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 1 2001MaurÍcio R Loureiro-Silva Abstract Background: We have shown that the portal hypertensive response to bradykinin in normal rats is mediated by B2 receptors. Methods: By using isolated and exsanguinated rat liver perfusion, we studied the portal hypertensive response to bradykinin or des-Arg9 -bradykinin (B1 agonist) in inflamed or cirrhotic rat livers. Livers were perfused with bovine serum albumin Krebs,Henseleit buffer (pH 7.4; 37°C) at a constant flow rate, in the absence or presence of des-Arg9[Leu8]-bradykinin or HOE 140 (B1 and B2 receptor antagonists, respectively). Bradykinin (140 nmol) or des-Arg9 -bradykinin was injected as a bolus via the afferent route to the liver. Results: Basal perfusion pressure in liver-cirrhotic rats was higher than in normal rats. In normal, inflamed, or liver-cirrhotic rats, the presence of the B1 antagonist did not change the portal hypertensive response to bradykinin, while the B2 antagonist abolished this response. A 140-nmol dose of des-Arg9 -bradykinin did not change the perfusion pressure; 700 nmol of this B1 agonist produced an insignificant perfusion pressure increase. The perfusion pressure increase induced by bradykinin in cirrhotic livers was lower than in normal livers. Conclusions: The portal hypertensive response to bradykinin in inflamed or cirrhotic rat livers is mediated by B2 receptors, but not B1 receptors, and there is a contracting hyporeactivity to bradykinin in cirrhotic rat livers. [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. 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