diethyl-maleate and Reperfusion-Injury

Systemic ischaemia-reperfusion (IR) injury is in part an oxidant injury mediated by neutrophils. Diethylmaleate (DEM), an intracellular pro-oxidant agent, has been shown to alleviate neutrophil-mediated tissue injury. The aim of this study was to evaluate whether DEM could have a protective effect on neutrophil-mediated lung injury in an animal model of lower-torso IR.. Sprague-Dawley rats (seven per group) were randomized into three groups. The control group underwent midline laparotomy only; the IR group underwent laparotomy and clamping of the infrarenal abdominal aorta for 30 min followed by 2 h of reperfusion; and the third group was pretreated with DEM 6 mmol/kg intraperitoneally 1 h before the IR insult.. IR resulted in a significant increase in both microvascular leakage and pulmonary neutrophil infiltration as measured by bronchoalveolar lavage protein concentration and pulmonary myeloperoxidase activity respectively. Pretreatment with DEM significantly attenuated both microvascular leakage and neutrophil infiltration.. Preconditioning with DEM protected against IR-induced lung injury. This protective effect raises the possibility of using pro-oxidants to prevent inflammatory injury.

Topics: Animals; Aorta; Constriction; Lung; Lung Diseases; Male; Maleates; Microcirculation; Neutrophils; Oxidants; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Reduced glutathione (GSH) is a major myocardial antioxidant. Since reperfusion phenomena such as ventricular fibrillation (VF) are associated with oxygen free radical production during ischaemia, myocardial GSH depletion might be expected to increase susceptibility to such phenomena. This possibility was tested in isolated rat hearts using diethylmaleate (DEM) or L-buthionine-SR-sulfoximine (BSO) to deplete myocardial GSH. High dose DEM (860 mg/kg) depleted myocardial GSH from a control mean of 7.64 +/- 0.73 to 3.18 +/- 0.56, low dose DEM (215 mg/kg) to 4.29 +/- 0.53 nmol/mg protein and BSO (4 mmol/kg) from a control mean of 6.94 +/- 0.54 to 2.18 +/- 0.14 nmol/mg protein. Hearts were perfused in the Langendorff mode at 37 degrees C with bicarbonate buffer (K+ = 4.3 mM). Regional ischaemia was induced for 5, 8.5, 10, 20 or 40 min (DEM groups: n = 10/treatment/time point) or 8.5 min only (BSO groups: n = 10/treatment) then hearts were reperfused for 5 min. Reperfusion VF incidence showed a classical "bell-shaped" curve, but there was no difference in VF incidence, VF time-to-onset, arrhythmia duration and "arrhythmia scores" between GSH-depleted and control hearts. Depleting myocardial GSH is not proarrhythmic for reperfusion-induced arrhythmias. It would appear GSH is not significantly involved in protecting against the oxidant stress of reperfusion, or conversely that the reserve of this redox system is so high only severe depletion might show an effect.

Topics: Animals; Buthionine Sulfoximine; Glutathione; Male; Maleates; Myocardial Reperfusion; Rats; Rats, Wistar; Reperfusion Injury; Time Factors; Ventricular Fibrillation; Ventricular Function

In the present study the influence of pretreatment with various GSH depletors such as buthionine sulfoximine (BSO) and diethylmaleate (DEM) was investigated in rats following cerebral post-ischemic reperfusion. Moreover, the effect of diethyldithiocarbamic acid (DDC), inhibitor of endogenous Cu,Zn-SOD, was evaluated. A significant depletion (40% of control value) of GSH levels was observed 24 h after DEM administration; after 48 h the value reached control levels. BSO showed maximal GSH depletion (59%) 24 h after administration and it was constant for almost 48 h. DDC administration caused a marked decrease (60%) of Cu,Zn-SOD activity 4 h after the injection and induced a marked decrease in percentage of survival with respect to control (untreated, ischemic) rats, when administered 4 h before ischemia. BSO and DEM prolonged the survival time of animals when administered 24 h before ischemia. This last paradoxical effect is unclear at present, but it might be due to an influence on glutamate cascade.

Topics: Animals; Brain; Buthionine Sulfoximine; Ditiocarb; Free Radical Scavengers; Free Radicals; Glutathione; Ischemic Attack, Transient; Kinetics; Male; Maleates; Methionine Sulfoximine; Rats; Rats, Wistar; Reperfusion Injury; Superoxide Dismutase

Alterations in cellular calcium homeostasis are a critical factor in the pathogenesis of hepatic ischemic damage and may mediate oxygen free radical injury during the reperfusion period. We investigated the effect of the calcium channel blocker verapamil on hepatic ischemia/reperfusion injury in normal rats and rats sensitized to oxidative injury by chemical depletion of the endogenous antioxidant glutathione. Forty-five minutes of complete hepatic ischemia followed by reperfusion caused an increase in the serum glutamic pyruvic transaminase (SGPT) level and a decline in the endogenous hepatic glutathione level but no increase in hepatic lipid peroxidation products. Chemical depletion of hepatic glutathione with diethylmaleate did not induce hepatocellular injury but augmented hepatic ischemia/reperfusion-induced SGPT release and promoted lipid peroxidation. Pretreatment with the calcium entry blocker verapamil protected against the ischemia/reperfusion-induced drop in hepatic glutathione but did not reduce SGPT release in normal rats. In rats sensitized to oxidative injury by chemical depletion of endogenous glutathione, the calcium channel blocker verapamil protected against ischemia/reperfusion-induced lipid peroxidation and reduced the release of SGPT. These findings indicate that the rat liver is protected against oxidative injury after short periods of total ischemia by its rich supply of endogenous glutathione. A beneficial effect of verapamil occurs only in rats sensitized to oxidative injury, suggesting that the calcium channel blocker protects against oxygen radical attack.

Topics: Alanine Transaminase; Animals; Glutathione; Lipid Peroxidation; Liver; Male; Maleates; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Verapamil

The role of oxygen-free radicals for metabolic derangements in the ischemic and reperfused liver is controversial. The effect on hepatic protein synthesis of a 60-minute period of ischemia followed by two hours of reperfusion was studied in four groups of rats with different hepatic contents of the oxygen free radical scavenger glutathione (GSH): group 1, fed rats; group 2, fed rats treated with diethylmaleate (DEM) one hour before use (0.69 mL/kg, i.p.); group 3, 48-hour fasted rats; and group 4, 48-hour fasted rats treated with cobalt-chloride (45 mg/kg, s.c.) ten hours before use. Protein synthesis rates were determined by measuring incorporation of U-14C-leucine into protein in incubated liver slices. Treatment of fed rats with DEM and fasting for 48 hours significantly reduced liver GSH content. The effect of fasting on liver GSH was reversed by treatment with cobalt-chloride. The protein synthesis rate was reduced to approximately 30% of initial value at the end of the ischemic period and recovered to 70% to 100% of initial value after two hours of reperfusion with no differences between the experimental groups. Thus the effect of liver ischemia and reperfusion on protein synthesis was similar in groups of rats with different hepatic GSH contents at the onset of ischemia. The data suggest that oxygen free radicals do not play a major role for the impairment of protein synthesis in the ischemic and reperfused liver.

Topics: Animals; Cobalt; Fasting; Glutathione; Ischemia; Leucine; Liver; Liver Glycogen; Male; Maleates; Protein Biosynthesis; Rats; Rats, Inbred Strains; Reperfusion Injury

Oxygen free radicals have been implicated as mediators of gastric mucosal injury caused by ischemia/reperfusion. We investigated the role of exogenous and endogenous glutathione (reduced glutathione, GSH) in gastric mucosal injury associated with hemorrhagic shock and reperfusion. Mucosal GSH content was found to be consistently higher in the antrum than in the corpus. Ischemia (hemorrhage to 25 to 30 mm Hg) followed by retransfusion of shed blood, but not ischemia alone, caused a marked drop in gastric mucosal GSH and gross mucosal injury, which was confined to the corpus and spared the antrum. Chemical depletion of gastric mucosal GSH with diethylmaleate or inhibition of GSH synthesis with buthionine sulfoximine increased mucosal injury in the corpus and also rendered the antral mucosa susceptible to ischemia/reperfusion injury. Pretreatment with exogenous GSH provided marked protection against gross mucosal ischemia/reperfusion injury and prevented the ischemia/reperfusion-induced drop in mucosal GSH. These data suggest that the mucosal availability of the antioxidant GSH is an important protective factor against the development of gastric mucosal ischemia/reperfusion injury and supports a major role of oxygen radical release in the pathogenesis of gastric ischemia/reperfusion injury.

Topics: Animals; Antimetabolites; Blood Transfusion; Buthionine Sulfoximine; Gastric Mucosa; Glutathione; Ischemia; Male; Maleates; Methionine Sulfoximine; Pyloric Antrum; Rats; Rats, Inbred Strains; Reperfusion Injury; Shock, Hemorrhagic; Stomach