EFFECT OF GLUTATHIONE ON CANINE MYOCARDIAL-ISCHEMIA WITHOUT REPERFUSION

The present study was to evaluate the effect of exogenous glutathione on myocardial damage resulting from permanent (no reperfusion) coronar y ligation (3 or 6 h) in anaesthetized dogs. Haemodynamics, infarct si ze and myocardial glutathione content were determined. Erythrocyte sup eroxide dismutase (SOD) activity was also determined in coronary venou s blood samples. Glutathione was administered by the intraperitoneal r oute, 100 mg kg-1 as initial dose given 5 min before coronary ligation , and successive doses of 25 mg kg-1 every 40 min throughout the study period. Saline-treated dogs showed myocardial infarction, a decrease in myocardial glutathione content, and a transient increase in SOD act ivity. Three hours occlusion in glutathione-treated dogs resulted in a small reduction of infarct size, and no changes in myocardial glutath ione content and SOD activity. By contrast, administration of glutathi one failed to reduce infarct size and failed to prevent myocardial glu tathione decrease in dogs subjected to 6 h occlusion. These results in dicate that exogenous glutathione is of minor beneficial effect for my ocardial damage resulting from permanent coronary occlusion and sugges t that endogenous glutathione has a limited role in protecting against myocardial ischaemia without reperfusion.