Isoflurane-sevoflurane adminstration before ischemia attenuates ischemia-reperfusion-induced injury in isolated rat lungs

BACKGROUND: The effects of volatile anesthetics on ischemia-reperfusion (IR)-induced lung injury are not clear. The authors investigated the effects of preadministration of isoflurane and sevoflurane on IR-induced lung injury in an isolated buffer-perfused rat lung model. METHODS: Isolated rat lungs were designated into four groups: control group (n = 6): perfusion for 120 min without ischemia; IR group (n = 6): interruption of perfusion and ventilation for 60 min followed by reperfusion for 60 min; sevoflurane (SEVO)-IR (n = 6) and isoflurane (ISO)-IR (n = 6) groups: 1 minimum alveolar concentration (MAC) isoflurane or sevoflurane was administered for 30 min, followed by 60 min ischemia, then 60 min reperfusion. The authors measured the coefficient of filtration (Kfc) of the lung, lactate dehydrogenase (LDH) activity, tumor necrosis factor alpha, and nitric oxide metabolites (nitrite + nitrate) in the perfusate and the wet-to-dry lung weight ratio. RESULTS: IR caused significant increases in the coefficient of filtration (approximately sevenfold at 60 min of reperfusion compared with baseline; P < 0.01), the wet-to-dry lung weight ratio, the rate of increase of lactate dehydrogenase activity, and tumor necrosis factor a in the perfusate, and caused a significant decrease in nitric oxide metabolites in the perfusate. Administration of 1 MAC isoflurane or sevoflurane before ischemia significantly attenuated IR-induced increases in the coefficient of filtration and the wet-to-dry lung weight ratio, inhibited increases in the rate of increase of lactate dehydrogenase activity and tumor necrosis factor alpha in the perfusate, and abrogated the decrease in nitric oxide metabolites in the perfusate. No difference was found between the SEVO-IR and ISO-IR groups. CONCLUSION: Isoflurane and sevoflurane administered before ischemia can attenuate IR-induced injury in isolated rat lungs.     

Effect of nutritional status on oxidative stress in an ex vivo perfused rat liver

BACKGROUND: Normothermic ischemia-reperfusion is a determinant in liver injury occurring during surgical procedures, ischemic state, and multiple organ failure. The preexisting nutritional status of the liver might contribute to the extent of tissue injury and primary nonfunction. The aim of this study was to determine the role of starvation on hepatic ischemia-reperfusion injury in normal rat livers. METHODS: Rats were randomly divided into two groups: one had free access to food, the other was fasted for 16 h. The portal vein was cannulated, and the liver was removed and perfused in a closed ex vivo system. Two modes of perfusion were applied in each series of rats, fed and fasting. In the ischemia-reperfusion mode, the experiment consisted of perfusion for 15 min, warm ischemia for 60 min, and reperfusion during 60 min. In the nonischemia mode, perfusion was maintained during the 135-min study period. Five rats were included in each experimental condition, yielding a total of 20 rats. Liver enzymes, potassium, glucose, lactate, free radicals, i.e., dienes and trienes, and cytochrome c were analyzed in perfusate samples. The proportion of glycogen in hepatocytes was determined in tissue biopsies. RESULTS: Transaminases, lactate dehydrogenase, potassium, and free radical concentrations were systematically higher in fasting rats in both conditions, with and without ischemia. Cytochrome c was higher after reperfusion in the fasting rats. Glucose and lactate concentrations were greater in the fed group. The glycogen content decreased in both groups during the experiment but was markedly lower in the fasting rats. CONCLUSIONS: In fed rats, liver injury was moderate, whereas hepatocytes integrity was notably impaired both after continuous perfusion and warm ischemia in fasting animals. Reduced glycogen store in hepatocytes may explain reduced tolerance.     

Effect of Nutritional Status on Oxidative Stress in an Ex Vivo Perfused Rat Liver

Background: Normothermic ischemia-reperfusion is a determinant in liver injury occurring during surgical procedures, ischemic state, and multiple organ failure. The preexisting nutritional status of the liver might contribute to the extent of tissue injury and primary nonfunction. The aim of this study was to determine the role of starvation on hepatic ischemia-reperfusion injury in normal rat livers.

Methods: Rats were randomly divided into two groups: one had free access to food, the other was fasted for 16 h. The portal vein was cannulated, and the liver was removed and perfused in a closed ex vivo system. Two modes of perfusion were applied in each series of rats, fed and fasting. In the ischemia-reperfusion mode, the experiment consisted of perfusion for 15 min, warm ischemia for 60 min, and reperfusion during 60 min. In the nonischemia mode, perfusion was maintained during the 135-min study period. Five rats were included in each experimental condition, yielding a total of 20 rats. Liver enzymes, potassium, glucose, lactate, free radicals, i.e., dienes and trienes, and cytochrome c were analyzed in perfusate samples. The proportion of glycogen in hepatocytes was determined in tissue biopsies.

Results: Transaminases, lactate dehydrogenase, potassium, and free radical concentrations were systematically higher in fasting rats in both conditions, with and without ischemia. Cytochrome c was higher after reperfusion in the fasting rats. Glucose and lactate concentrations were greater in the fed group. The glycogen content decreased in both groups during the experiment but was markedly lower in the fasting rats.     

Isoflurane-Sevoflurane Administration before Ischemia Attenuates Ischemia-Reperfusion-induced Injury in Isolated Rat Lungs

Background: The effects of volatile anesthetics on ischemia-reperfusion (IR)-induced lung injury are not clear. The authors investigated the effects of preadministration of isoflurane and sevoflurane on IR-induced lung injury in an isolated buffer-perfused rat lung model.

Methods: Isolated rat lungs were designated into four groups: control group (n = 6): perfusion for 120 min without ischemia; IR group (n = 6): interruption of perfusion and ventilation for 60 min followed by reperfusion for 60 min; sevoflurane (SEVO)-IR (n = 6) and isoflurane (ISO)-IR (n = 6) groups: 1 minimum alveolar concentration (MAC) isoflurane or sevoflurane was administered for 30 min, followed by 60 min ischemia, then 60 min reperfusion. The authors measured the coefficient of filtration (Kfc) of the lung, lactate dehydrogenase (LDH) activity, tumor necrosis factor [alpha], and nitric oxide metabolites (nitrite + nitrate) in the perfusate and the wet-to-dry lung weight ratio.

Results: IR caused significant increases in the coefficient of filtration (approximately sevenfold at 60 min of reperfusion compared with baseline;P < 0.01), the wet-to-dry lung weight ratio, the rate of increase of lactate dehydrogenase activity, and tumor necrosis factor [alpha] in the perfusate, and caused a significant decrease in nitric oxide metabolites in the perfusate. Administration of 1 MAC isoflurane or sevoflurane before ischemia significantly attenuated IR-induced increases in the coefficient of filtration and the wet-to-dry lung weight ratio, inhibited increases in the rate of increase of lactate dehydrogenase activity and tumor necrosis factor [alpha] in the perfusate, and abrogated the decrease in nitric oxide metabolites in the perfusate. No difference was found between the SEVO-IR and ISO-IR groups.     

Differential effects of halothane,enflurane, isoflurane,and sevoflurane on the hemodynamics and metabolism in the perfused rat liver in fasted rats

The effects of volatile anesthetics on hepatic hemodynamics and metabolism were studied using isolated liver perfusion. The liver was isolated from overnight-fasted male Sprague-Dawley rats and placed in a recirculating perfusion-aeration system. The liver was perfused through the portal vein at a constant pressure of 12 cmH₂O. Four volatile anesthetics, halothane, enflurane, isoflurane, and sevoflurane, were administered at concentrations identical to 1 and 2 times the minimal alveolar concentration (MAC). All the anesthetics maintained hepatic flow and decreased hepatic oxygen consumption. Among the anesthetics tested, isoflurane produced the largest decrease in hepatic oxygen consumption. At 2 MAC, the percent decrease in oxygen consumption by isoflurane was significantly greater than that by halothane. The increase in lactate concentration in the recirculating perfusate was significantly enhanced by the volatile anesthetics, and the enhancement was less remarkable in the isofluranetreated group than in the enflurane-or sevoflurane-treated groups. These results indicate that volatile anesthetics alter hepatic carbohydrate metabolism but maintain hepatic blood flow when the perfusion pressure is kept constant. Isoflurane exerts exceptional influence on hepatic oxygen consumption and lactate production, and may be preferable for operations that limit the oxygen supply to the liver.     

Effects of volatile anesthetics on the calcium ionophore A23187-mediated alterations in hepatic flow and metabolism in the perfused liver in fasted rats

Alterations in intracellular calcium homeostasis have been implicated in hepatic injury. Volatile anesthetics modulate the homeostasis of intracellular calcium.
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. The liver was isolated from 24 hr-fasted male Sprague-Dawley rats, and perfused through the portal vein at a constant pressure of 1.2 kPa in a recirculating perfusion-aeration system. Halothane, isoflurane and sevoflurane were administered at 2%, 3% and 4.4%, respectively.
All volatile anesthetics maintained basal hepatic flow, reduced oxygen consumption, and transiently enhanced net lactate production. A23187 at initial concentrations of 0.8 to 3.2 μM decreased hepatic flow and oxygen consumption in a dose-de pendent manner, and enhanced lactate production. All anesthetics significantly attenuated the decreases in hepatic flow and oxygen consumption after administration of A23187 at 1.6 μM. None of the anesthetics significantly influenced the A23187-induced enhancement of net lactate production.
Volatile anesthetics may attenuate the hepatic vasoconstriction and oxygen debt induced by intracellular calcium overload.     

Sevoflurane and isoflurane do not enhance the pre- and postischemic eicosanoid production in guinea pig hearts

Eicosanoids and volatile anesthetics can influence cardiac reperfusion injury. Accordingly, we analyzed the effects of sevoflurane and isoflurane applied in clinically relevant concentrations on the myocardial production of prostacyclin and thromboxane A2 (TxA2) and on heart function. Isolated guinea pig hearts, perfused with crystalloid buffer, performed pressure-volume work. Between two working phases, hearts were subjected to 15 min of global ischemia followed by reperfusion. The hearts received no anesthetic, 1 minimum alveolar anesthetic concentration (MAC) isoflurane (1.2 vol%), or 0.5 and 1 MAC sevoflurane (1 vol% and 2 vol%), either only preischemically or pre- and postischemically. In additional groups, cyclooxygenase function was examined by an infusion of 1 microM arachidonic acid (AA) in the absence and presence of sevoflurane. The variables measured included the myocardial production of prostacyclin, TxA2 and lactate, consumption of pyruvate, coronary perfusion pressure, and the tissue level of isoprostane 8-iso-PGF2alpha. External heart work, determined pre- and postischemically, served to assess recovery of heart function. Volatile anesthetics had no impact on postischemic recovery of myocardial function (50%-60% recovery), perfusion pressure, lactate production, or isoprostane content. Release of prostacyclin and TxA2 was increased in the early reperfusion phase 5-8- and 2-4-fold, respectively, indicating enhanced AA liberation. Isoflurane and sevoflurane did not augment the eicosanoid release. Only 2 vol% sevoflurane applied during reperfusion prevented the increased eicosanoid formation in this phase. Infusion of AA increased prostacyclin production approximately 200-fold under all conditions, decreased pyruvate consumption irreversibly, and markedly attenuated postischemic heart work (25% recovery). None of these effects were mitigated by 2 vol% sevoflurane. In conclusion, only sevoflurane at 2 vol% attenuated the increased liberation of AA during reperfusion. Decreased eicosanoid formation had no effect on myocardial recovery in our experimental setting while excess AA was deleterious. Because eicosanoids influence intravascular platelet and leukocyte adhesion and activation, sevoflurane may have effects in reperfused tissues beyond those of isoflurane. IMPLICATIONS: In an isolated guinea pig heart model, myocardial eicosanoid release was not increased by isoflurane or sevoflurane, either before or after ischemia. Sevoflurane (2 vol%) but not isoflurane attenuated the increased release of eicosanoids during reperfusion.     

Isoflurane Attenuates Early Neutrophil-independent Hypoxia-Reoxygenation Injuries in the Reperfused Liver in Fasted Rats

Background: Ischemia-hypoxia followed by reperfusion and reoxygenation injures cells and organs. Previous studies have indicated that isoflurane may protect organs from ischemia-reperfusion or hypoxia-reoxygenation. This study investigated the ability of isoflurane to protect the liver from hypoxia-reoxygenation injury and the mechanisms of this phenomenon.

Methods: The isolated liver was perfused at a constant pressure of 12 cm H2 O with a modified Krebs-Ringer-bicarbonate solution saturated with a 95% oxygen/5% carbon dioxide gas mixture. Hypoxic perfusion produced by decreasing the oxygen concentration in the gas mixture to 10% was followed by perfusion at 95% oxygen for 60 min. Viability of the liver was assessed by lactate dehydrogenase release from the liver. Isoflurane at 0.5, 1, and 2 minimum alveolar concentration was administered to assess the effect of isoflurane on hypoxia-reperfusion injury. To determine the effect of isoflurane on extracellular generation of superoxide in the liver, the reduction of ferricytochrome c with or without superoxide dismutase was measured.

Results: Lactate dehydrogenase release was transiently but dramatically increased by reoxygenation and significantly attenuated by 1 and 2 minimum alveolar concentration of isoflurane. Suppression of Kupffer cells with gadolinium chloride also attenuated the lactate dehydrogenase release. Isoflurane significantly reduced the superoxide generation on reperfusion.     

Absence of Direct Antioxidant Effects from Volatile Anesthetics in Primary Mixed Neuronal-Glial Cultures

Background: Volatile anesthetics decrease ischemic brain injury. Mechanisms for this protection remain under investigation. The authors hypothesized that volatile anesthetics serve as antioxidants in a neuronal-glial cell culture system.

Methods: Primary cortical neuronal-glial cultures were prepared from fetal rat brain. Cultures were exposed to iron, H2O2, or xanthine-xanthine oxidase for 30 min in serum-free media containing dissolved isoflurane (0-3.2 mm), sevoflurane (0-3.6 mm), halothane (0-4.1 mm), n-hexanol, or known antioxidants. Cell damage was assessed by release of lactate dehydrogenase (LDH) and trypan blue exclusion 24 h later. Lipid peroxidation was measured by the production of thiobarbituric acid-reactive substances in a cell-free lipid system. Iron and calcium uptake and mitochondrial depolarization were measured after exposure to iron in the presence or absence of isoflurane.

Results: Deferoxamine reduced LDH release caused by H2O2 or xanthine-xanthine oxidase, but the volatile anesthetics had no effect. Iron-induced LDH release was prevented by the volatile anesthetics (maximum effect for halothane = 1.2 mm, isoflurane = 1.2 mm, and sevoflurane = 2.1 mm aqueous phase). When corrected for lipid solubility, the three volatile anesthetics were equipotent against iron-induced LDH release. In the cell-free system, there was no effect of the anesthetics on thiobarbituric acid-reactive substance formation in contrast to Trolox, which provided complete inhibition. Isoflurane (1.2 mm) reduced mean iron uptake by 46% and inhibited mitochondrial depolarization but had no effect on calcium uptake.     

Absence of direct antioxidant effects from volatile anesthetics in primary mixed neuronal-glial cultures

BACKGROUND: Volatile anesthetics decrease ischemic brain injury. Mechanisms for this protection remain under investigation. The authors hypothesized that volatile anesthetics serve as antioxidants in a neuronal-glial cell culture system. METHODS: Primary cortical neuronal-glial cultures were prepared from fetal rat brain. Cultures were exposed to iron, H2O2, or xanthine-xanthine oxidase for 30 min in serum-free media containing dissolved isoflurane (0-3.2 mm), sevoflurane (0-3.6 mm), halothane (0-4.1 mm), n-hexanol, or known antioxidants. Cell damage was assessed by release of lactate dehydrogenase (LDH) and trypan blue exclusion 24 h later. Lipid peroxidation was measured by the production of thiobarbituric acid-reactive substances in a cell-free lipid system. Iron and calcium uptake and mitochondrial depolarization were measured after exposure to iron in the presence or absence of isoflurane. RESULTS: Deferoxamine reduced LDH release caused by H2O2 or xanthine-xanthine oxidase, but the volatile anesthetics had no effect. Iron-induced LDH release was prevented by the volatile anesthetics (maximum effect for halothane = 1.2 mm, isoflurane = 1.2 mm, and sevoflurane = 2.1 mm aqueous phase). When corrected for lipid solubility, the three volatile anesthetics were equipotent against iron-induced LDH release. In the cell-free system, there was no effect of the anesthetics on thiobarbituric acid-reactive substance formation in contrast to Trolox, which provided complete inhibition. Isoflurane (1.2 mm) reduced mean iron uptake by 46% and inhibited mitochondrial depolarization but had no effect on calcium uptake. CONCLUSIONS: Volatile anesthetics reduced cell death induced by oxidative stress only in the context of iron challenge. The likely reason for protection against iron toxicity is inhibition of iron uptake and therefore indirect reduction of subsequent intracellular oxidative stress caused by this challenge. These data argue against a primary antioxidant effect of volatile anesthetics.     

麦角新碱预处理对减轻大鼠移植肝缺血再灌注损伤的作用

目的 探讨使用外源性药物麦角新碱预处理对减轻大鼠移植肝缺血再灌注损伤的作用.方法 在大鼠的门静脉-左肾静脉搭桥、肝后下腔静脉内置管分流法自体原位肝移植模型中,于肝门阻断前10 min经大鼠尾静脉注射麦角新碱;观察移植肝缺血前和再灌注后5 min、30 min、2 h时血清一氧化氮(NO)和血浆内皮素1(ET1)水平以及NO/ET1的比值变化;测定血清丙氨酸转氨酶(ALT)酶学差异和肝组织内三磷酸腺苷(ATP)和丙二醛(MDA)含量变化;再灌注2 h取肝组织检测肝细胞、肝小叶超微结构.结果 应用麦角新碱预处理的大鼠移植肝缺血前门脉血浆中ET1升高(P＜0.01),但再灌注后5 min、30 min时,血浆中ET1水平降低(P＜0.05);而缺血前NO/ET1比值降低(P＜0.01),再灌注后5 min时,NO/ET1比值升高(P＜0.01);再灌注后ALT的升高有逐渐降低趋势;再灌注后2 h肝细胞内超微结构的损害程度减轻.结论 使用麦角新碱预处理能减轻大鼠移植肝缺血再灌注损伤.移植肝缺血再灌注损伤的靶细胞是肝血窦内皮细胞,NO/ET1比值平衡可能是影响移植肝微循环血流量变化的调节因素.     

N-乙酰半胱氨酸对鼠肝冷缺血/再灌注损伤的保护作用

目的 为提高肝移植手术后供肝存活率,研究抗氧化剂Ｎ－乙酰半胱氨酸（ＮＡＣ）预处理是否能减少移植肝的冷缺血／再灌注损伤。方法 从大鼠肠系膜上静脉分别注入ＮＡＣ１５mg/kg或５％葡萄糖1ml,15min后取肝,以４℃ＵＷ液保存４８h,再将鼠肝置于离体灌注仪上循环灌流2h。取各时点样本测转氨酶、乳酸、酸性磷酸酶和ＡＴＰ。使用谷胱甘肽合成抑制剂ＢＳＯ处理组,在取肝前2h经用腔注射ＢＳＯ3mmol/kg。结果 ＮＡＣ可以减少鼠肝冷缺血／再灌注后ＡＳＴ、ＡＬＴ和ＬＤＨ释放,提高胆汁分泌量。ＮＡＣ抑制离体鼠肝酸性磷酸酶释放。用谷胱甘肽合成抑制剂ＢＳＯ预处理后,ＮＡＣ减少ＡＳＴ、ＡＬＴ和ＬＤＨ释放,提高胆汁产量的作用依然存在。结论 ＮＡＣ可抑制鼠肝冷缺血／再灌注损伤,其保护作用与直接抑制枯否细胞激活有关,而与促肝细胞谷胱甘肽合成作用无关。     

Increased sinusoidal pressure is associated with early liver weight gain in ischemia-reperfusion injury in isolated perfused rat liver

BACKGROUND: Hepatic ischemia-reperfusion (I/R) is accompanied by liver weight gain and ascites formation. This could be caused by an increase in sinusoidal pressure, a determinant of hepatic transvascular fluid movement. We determined the role of sinusoidal pressure, assessed by triple vascular occlusion pressure (P(to)), in the I/R injury in isolated rat livers perfused with leukocyte-free diluted blood bivascularly via the portal vein and hepatic artery. MATERIALS AND METHODS: Ischemia was induced at room temperature by occlusion of either the inflow lines of the hepatic artery and portal vein (the open outflow group, n = 10) or both the inflow and the outflow (hepatic venous) lines (the closed outflow group, n = 10) for 1 h, followed by 1-h reperfusion in a recirculating manner. RESULTS: Liver weight in both groups increased biphasically after reperfusion; the initial peak occurred at 3 min and the second peak at 60 min. Immediately after reperfusion, P(to) peaked, followed by a gradual decline. The initial weight increase in groups combined was significantly and positively correlated with an increase in P(to) (r = 0.716, P = 0.0002), but the second peak was independent of P(to). Liver injury, assessed by perfusate levels of hepatic enzymes and reduced bile flow rate, was observed at 60 min after reperfusion in both groups. CONCLUSIONS: These findings suggest that increased sinusoidal pressure contributes to only the early liver weight gain after reperfusion in isolated perfused rat livers. The late weight gain may be presumably due to liver injury.     

Isoflurane administration before ischemia and during reperfusion attenuates ischemia/reperfusion-induced injury of isolated rabbit lungs.

To investigate the effects of isoflurane on ischemia/ reperfusion (IR)-induced lung injury, we administered isoflurane before ischemia or during reperfusion. Isolated rabbit lungs were divided into the following groups: control (n = 6), perfused and ventilated for 120 min without ischemia; ISO-control (n = 6), 1 minimum alveolar anesthetic concentration (MAC) isoflurane was administered for 30 min before 120 min continuous perfusion; IR (n = 6), ischemia for 60 min, followed by 60 min reperfusion; IR-ISO1 and IR-ISO2, ischemia followed by reperfusion and 1 MAC (n = 6) or 2 MAC (n = 6) isoflurane for 60 min; ISO-IR (n = 6), 1 MAC isoflurane was administered for 30 min before ischemia, followed by IR. During these maneuvers, we measured total pulmonary vascular resistance (Rt), coefficient of filtration (Kfc), and lung wet to dry ratio (W/D). The results indicated that administration of isoflurane during reperfusion inhibited an IR-induced increase in Kfc and W/D ratio. Furthermore, isoflurane at 2 MAC, but not 1 MAC, significantly inhibited an IR-induced increase in Rt. The administration of isoflurane before ischemia significantly attenuated the increase in IR-induced Kfc, W/D, and Rt. IMPLICATIONS: Our results suggest that the administration of isoflurane before ischemia and during reperfusion protects against ischemia-reperfusion-induced injury in isolated rabbit lungs.     

Protection of the rat liver against rewarming ischemic injury by University of Wisconsin solution

BACKGROUND/AIM: University of Wisconsin (UW) solution has been proven able to prevent liver injury during cold ischemia. During rewarming ischemia, however, the efficacy of this solution in preserving hepatocyte function is unclear. The aim of the present study was to investigate to what extent UW solution protects rat liver during rewarming ischemia. METHODS: Livers were washed out with cool physiologic saline or with UW solution and subjected to rewarming ischemia for periods of 20 min or 45 min followed by reperfusion using a blood-free perfusion model. RESULTS: In comparison with controls, ischemia for 20 min in saline-treated livers led to mild depression of hepatocyte function, while UW solution afforded complete protection of the liver. In UW-treated livers, compared with saline-treated livers exposed to ischemia for 45 min, portal flow was slightly but significantly higher, bile production was increased by 62%, and lactate dehydrogenase leakage into the perfusate was reduced by 61%. In an attempt to explain mechanisms of liver protection by UW solution, we found that UW solution inhibited conversion of hypoxanthine into uric acid, but this effect was not associated with decreased degradation of adenine nucleotides in the liver during ischemia. Following 30 min reperfusion, UW solution increased tissue levels of adenosine triphosphate (not significantly) and adenosine diphosphate (significantly). Further, UW solution markedly reduced tumor necrosis factor-alpha release by the liver both after ischemia and after reperfusion. CONCLUSIONS: These results create the hypothesis that UW solution may protect liver tissue during ischemia in liver surgery as well as during the implantation stage of liver transplantation.     

Sevoflurane and Isoflurane Protect the Reperfused Guinea Pig Heart by Reducing Postischemic Adhesion of Polymorphonuclear Neutrophils

Background: Polymorphonuclear neutrophils (PMNs) contribute to reperfusion injury. Because volatile anesthetics can reduce PMN adhesion in the reperfused, nonworking heart, the authors analyzed whether this action of volatile anesthetics affects cardiac performance after ischemia and reperfusion and further clarified the underlying mechanism.

Methods: Isolated guinea pig hearts perfused with crystalloid buffer and performing pressure-volume work were used. Hearts were subjected to 15 min global ischemia and 20 min reperfusion. In the intervention groups an intracoronary bolus of 3 x 106 PMNs was applied in the second min of reperfusion, either in the absence or presence of 0.5 or 1 minimum alveolar concentration sevoflurane or isoflurane. The number of sequestered PMNs was calculated from the difference between coronary input and output (coronary effluent) of PMNs. Performance of external heart work, determined pre- and postischemically, served as criterion for recovery of myocardial function. Additionally, the expression of the integrin CD11b on the cell surface of PMN was measured before and after coronary passage.

Results: Injection of PMN in the reperfusion phase, but not under nonischemic conditions, reduced recovery of external heart work significantly (from 55 +/- 7% to 19 +/- 11%). Addition of sevoflurane or isoflurane in concentrations of 0.5 and 1 minimum alveolar concentration to the perfusate reduced postischemic PMN adhesion from 36 +/- 8% to basal values (20 +/- 7%) and prevented decline of cardiac function. CD11b expression on PMNs increased significantly during postischemic coronary passage under control conditions. Again, both anesthetics in both concentrations inhibited that activation.     

Neutrophils pretreated with volatile anesthetics lose ability to cause cardiac dysfunction

BACKGROUND: Volatile anesthetics can precondition the myocardium against functional depression and infarction following ischemia-reperfusion. Neutrophil activation, adherence, and release of superoxide play major roles in reperfusion injury. The authors tested the hypothesis that pretreatment of neutrophils with a volatile anesthetic, i.e., simulated preconditioning, can blunt their ability to cause cardiac dysfunction. METHODS: Studies were performed in 60 buffer-perfused and paced isolated rat hearts. Left ventricular developed pressure served as an index of myocardial contractility. Polymorphonuclear neutrophils and/or drugs were added to coronary perfusate for 10 min, followed by 30 min of recovery. Platelet-activating factor was used to stimulate neutrophils. Pretreatment of neutrophils consisted of incubation with 1.0 minimum alveolar concentration (MAC) isoflurane or sevoflurane for 15 min, followed by washout. Additional studies were performed with 0.25 MAC isoflurane. Effects of superoxide dismutase were compared to those of volatile anesthetics. Superoxide production was measured by spectrophotometry. Neutrophil adherence to coronary vascular endothelium was estimated from the difference between neutrophils administered and recovered in coronary venous effluent. RESULTS: Activated neutrophils caused marked, persistent reduction (> 50%) in left ventricular developed pressure. Isoflurane and sevoflurane at 1.0 MAC and superoxide dismutase abolished this effect. Isoflurane and sevoflurane reduced superoxide production of activated neutrophils by 29% and 33%, respectively, and completely prevented the platelet-activating factor-induced increases in neutrophil adherence. Isoflurane at 0.25 MAC blunted, but did not abolish, the neutrophil-induced decreases in left ventricular developed pressure. CONCLUSION: Neutrophils pretreated with 1.0 MAC isoflurane or sevoflurane lost their ability to cause cardiac dysfunction, while those pretreated with a concentration of isoflurane as low as 0.25 MAC were partially inhibited. This action of the volatile anesthetics was associated with reductions in superoxide production and neutrophil adherence to the coronary vascular endothelium. Our findings suggest that inhibitory actions on neutrophil activation and neutrophil-endothelium interaction may contribute to the preconditioning effects of volatile anesthetics observed in vivo during myocardial ischemia-reperfusion.     

The effect of halothane, isoflurane, and verapamil on ischemic-isolated rabbit renal tubules

The effects of the volatile anesthetics halothane and isoflurane, and the calcium entry blocker verapamil, were studied in isolated rabbit renal tubules under nonischemic and simulated ischemic conditions. Isolated rabbit renal tubules were subjected to zero (control), 30 (I-30), or 60 (I-60) minutes of simulated ischemia following the method of Weinberg. Following the ischemic period, tubules were reoxygenated in a Gilson respirometer (simulated reperfusion) and treated with either halothane (1%) or isoflurane (1%) in the controls and at I-30, or halothane (1%, 2%, 4%) or verapamil (5 microM, 15 microM, 30 microM) at I-60. Tubules were analyzed for lactate dehydrogenase (LDH) release (measuring cell membrane integrity), intracellular potassium and adenosine triphosphate (ATP), and oxygen consumption (cellular respiratory rate). In nonischemic tubules, exposure to 1% isoflurane caused significantly reduced LDH release compared with that released by controls, indicating cell membrane protection, whereas 1% halothane had no effect on these cells. With 30 min of ischemia, 1% isoflurane was associated with significantly higher cellular LDH release and lower ATP concentration, suggesting increased cellular damage. Halothane (1%) was associated with only an increased ATP concentration in tubules exposed to 30 min of ischemia. Following 60 min of ischemia, halothane (4%) decreased LDH release by 45% (29.2 +/- 2.3% vs. 47.0 +/- 9.6% without halothane). Tubules exposed to halothane also had higher intracellular potassium and ATP concentrations, and increased respiratory rates. Halothane (2%) was less protective and only increased the ATP concentration. The release of LDH was not statistically different with or without 2% halothane.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of intraportal prostaglandin E1 on adhesion molecule expression, inflammatory modulator function, and histology in canine hepatic ischemia/reperfusion injury

BACKGROUND: Prostaglandin E1 (PGE1) is known to protect the liver from I/R, however, the mechanism of cytoprotection is not well understood. This study investigates the effect of intraportal infusion of PGE1 in a warm liver ischemia/reperfusion (I/R) model on cytokines, adhesion molecules and liver structure. MATERIALS AND METHODS: Twenty dogs underwent laparotomy under general anesthesia. PGE1 (0.02 microg\kg\min) was perfused through the portal vein in the PGE1 group (n = 10), or a similar volume of Ringer's solution in the control group (n = 10) for 15 min. Liver ischemia was induced by hepatic artery and portal vein occlusion and PGE1 was infused via the portal vein for 60 min. The occlusion was released and PGE1 infusion recommenced for 30 min. Blood and liver biopsies were sampled at baseline, 60 min ischemia, and 30 min reperfusion and assessed for transaminases, cytokines, adhesion molecules, and electron microscopy. RESULTS: PGE1 infusion significantly reduced transaminases TNF-alpha, sICAM-1, sP-selectin, and sE-selectin on ischemia and reperfusion. PGE1 reduced hepatocytic degeneration, portal and central ICAM-1 expression, central and sinusoidal VCAM-1 expression, portal and central P-selectin expression, and portal and sinusoidal E-selectin expression on reperfusion. CONCLUSION: Intraportal PGE1 infusion reduced I/R injury and was associated with down-regulation of ICAM-1, VCAM-1, P-selectin, and E-selectin on reperfusion.     

Comparison of Inflammatory Markers Between the Sevoflurane and Isoflurane Anesthesia in a Rat Model of Liver Ischemia/Reperfusion Injury

BackgroundSevoflurane and isoflurane had been reported to improve ischemia/reperfusion injury (I/R) through amelioration of the inflammatory response. We aimed to explore and compare the molecular mechanisms involved in sevoflurane and isoflurane anesthesia in liver ischemia-reperfusion of rat model.MethodsForty male Wistar rats were randomly divided into 4 groups: sham group, I/R group, sevoflurane group, and isoflurane group. The liver I/R injury model was established to investigate the effect of sevoflurane and isoflurane anesthesia on liver ischemia/reperfusion. The inflammatory markers and complement C3, C5a, and C6 were detected by enzyme-linked immunosorbent assay. Oxidative stress was detected by measuring the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO).ResultsOur results showed that sevoflurane anesthesia significantly decreased alanine transaminase, aspartate transaminase, and lactate dehydrogenase levels compared with isoflurane and controls. Sevoflurane inhibited I/R injury induced production of tumor necrosis factor α, interleukin 1, interleukin 6, and intercellular cell adhesion molecule-1 and promoted interleukin 10 production more significantly compared with isoflurane. Reduced MDA and NO and elevated SOD release suggested that oxidative stress was attenuated by sevoflurane and isoflurane anesthesia. Both sevoflurane and isoflurane anesthesia significantly decreased plasma C3 levels compared with the I/R injury group without differences.ConclusionSevoflurane anesthesia produced a more significant inhibitive effect on inflammatory cytokines and oxidative stress in liver I/R injury model than isoflurane, suggesting that sevoflurane is more suitable in surgery.