Effects of inhalation anesthesia on hepatic metabolism, Kupffer cell activation and stress protein induction during ischemia-reperfusion

虽然术中肝脏缺血/缺氧-再灌注/再氧合通常发生在全身麻醉下，但由于这一现象，挥发性麻醉剂对肝损伤的直接影响尚不清楚。采用离体肝灌注法研究了挥发性麻醉药对缺血/缺氧再灌注损伤的影响。从禁食24小时的雄性Sprague-Dawley大鼠中分离肝脏，在循环灌注通气系统中用改良的Krebs-Ringer碳酸氢盐溶液通过门静脉灌注。将基底层灌注压力从1.2降低至0.2 kPa，再灌注至基线水平，诱导缺血。将混合气体中的氧气浓度从95%降低到10%，然后在95%的氧气下再充氧，产生低氧灌注。通过肝脏乳酸脱氢酶（LDH）的释放来评估肝脏的活力。为了确定挥发性麻醉药对肝细胞外生成过氧化氢的影响，测定了有或没有超氧化物歧化酶时铁细胞色素c的减少。缺血是明显的减少氧输送到肝脏，并导致乳酸生产增加。再灌注引起乳酸摄取的短暂增加和LDH释放的显著增加。氟烷、异氟烷和七氟烷显著降低再灌注时LDH的释放。异氟醚对LDH释放的抑制作用在再灌注期明显，而在缺血期则不明显。这些结果表明，挥发性麻醉剂可能通过在再灌注阶段起作用，保护空腹肝脏免受早期、不依赖中性粒细胞的缺血再灌注损伤。再氧化可使LDH释放短暂但显著增加，异氟醚最低浓度为1和2时，LDH释放显著减弱。用氯化钆抑制Kupffer细胞也能减弱LDH的释放。异氟醚显著减少再灌注时超氧化物的产生。这些结果表明，异氟醚可以保护肝脏免受可能由Kupffer细胞介导的早期再氧化损伤。异氟醚抑制损伤的机制可能与抑制再氧化过程中细胞外超氧化物的产生有关。将游离细胞灌注的离体大鼠肝脏暴露于不同时期的缺血再灌注或缺氧再氧化。灌注时测定肝脏耗氧量和丙氨酸转氨酶渗漏。用northern印迹法分析灌注后肝脏主要应激蛋白热休克蛋白70的基因表达。热休克蛋白70 mRNA的表达随着再灌注时间的延长而增强。分级缺血或缺氧后的表达水平与计算出的肝氧比显著相关（r^2=0.737, p<0.001, n=21）。这些结果表明，热休克蛋白70mrna的积累反映了缺血再灌注和缺氧再氧化损伤的严重程度，并且在没有形成血液元素的情况下可以触发再灌注应激反应。细胞内钙稳态的改变与缺血再灌注损伤有关。采用离体禁食大鼠肝灌注实验，研究了挥发性麻醉剂对钙离子载体A23187诱导的血流动力学和代谢改变的影响。氟烷、异氟烷和七氟烷维持了基本的肝流量，减少了氧气消耗，并短暂地提高了净乳酸产量。所有麻醉药均能显著减轻A23187给药后肝血流和耗氧量的下降。挥发性麻醉剂可减轻细胞内钙超载引起的肝血管收缩和氧债。少

Although intraoperative ischemia/hypoxia-reperfusion/reoxygenation of the liver generally occurs under general anesthesia, little is known about the direct effect of volatile anesthetic agents on hepatic injury due to this phenomenon. The effect of volatile anesthetics on ischemia/hypoxia-reperfusion injury was studied using isolated liver perfusion.The liver was isolated from 24h-fasted, male Sprague-Dawley rats and perfused through the portal vein with a modified Krebs-Ringer bicarbonate solution in a recirculating perfusion-aeration system. Ischemia was induced by reducing the bascline perfusion pressure from 1.2 to 0.2 kPa followed by reperfusion to baseline level. Hypoxic perfusion was produced by decreasing the oxygen concentration in the gas mixture from 95% to 10% followed by reoxygenation at 95% oxygen. Viability of the liver was assessed by lactate dehydrogenase (LDH) release from the liver. To determine the effect of volatile anesthetics on the extracellular generation of su … More peroxide in the liver, the reduction of ferricytochrome c with or without superoxide dismutase was measured.Ischemia was evident by reduced oxygen delivery to the liver, and caused an increase in lactate production. Reperfusion caused a transient increase in lactate uptake and a significant increase in LDH release. Halothane, isoflurane and sevoflurane significantly attenuated LDH release during reperfusion. The suppression of LDH release was evident even when isoflurane was administered mainly during reperfusion period, but not when it was administered mainly during ischemia. These results indicate that volatile anesthetics may protect the fasted liver from carly, neutrophil-independent, ischemia reperfusion injury by acting during the reperfusion phase.LDH release was transiently but dramatically increased by reoxygenation and significantly attenuated by 1 and 2 minimum alvcolar concentrations of isoflurane. Suppression of Kupffer cells with gadolinium chloride also attenuated the LDH release. Isoflurane significantly reduced the superoxide generation on reperfusion. These results show that isoflurane protected the liver from early reoxygenation injury presumably mediated by Kupffer cells. The mechanisms of the inhibitory effect of isoflurane on the injury may involve suppression of extracellular superoxide generation during reoxygenation.Isolated rat livers with cell free perfusion were exposed to various periods of ischemia-reperfusion or hypoxia-reoxygenation. Hepatic oxygen consumption and alanine aminotransferase leakage from liver were determined during perfusion. The gene expression of heat shock protein 70, a major stress protein, of the liver was analyzed by Nothern blotting after perfusion. The expression of heat shock protein 70 mRNA augmented as the reperfusion period increased. The expression level after graded ischemia or hypoxia significantly correlated with the calculated hepatic oxygen bebt (r^2=0.737, p<0.001, n=21). These results suggest that accumulation of heat shock protein 70 mRNA reflects the severity of ischemia-reperfuion and hypoxia-reoxygenation injuries, and that stress response in reperfusion can be triggered without formed elements of blood.Altcrations in intracellular calcium homeostasis have been implicated in ischemia-reperfusion injuries. The effects of volatile anesthetics on the hemodynamic and metabolic alterations induced by the calcium ionophore A23187 were studied using isolated liver perfusion in fasted rats. Halothane, isoflurane and sevoflurane maintained basal hepatic flow, reduced oxygen consumption, and transiently enhanced net lactate production. All anesthetics significantly attenuated the decreases in hepatic flow and oxygen consumption after the administration of A23187. Volatile anesthetics may attenuate the hepatic vasoconstriction and oxygen debt induced by intracellular calcium overload. Less