Flow cytometric analysis of peroxidative activity in granulocytes from coronary and peripheral blood in acute myocardial ischemia and reperfusion in dogs: protective effect of methionine.

BACKGROUND: Methionine has shown protective effects in experimental models of myocardial infarction and is highly reactive to oxidative compounds produced by polymorphonuclear leukocytes (PMN), which in turn have been associated with myocardial damage. We have investigated the effect of methionine administration on spontaneous leukocyte peroxidative activity in myocardial ischemia and reperfusion. METHODS: In anesthetized dogs, with coronary occlusion (90 min) and reperfusion (90 min), PMN activation was measured by flow cytometric determination of H(2)O(2) with dihydrorhodamine 123, and correlated to hemodynamic parameters and infarct presence. To assess a possible direct effect of methionine, H(2)O(2) and superoxide were measured by flow cytometry in dog leukocyte suspensions following in vitro stimulation with f-MLP. RESULTS: PMN peroxidative activity in saline-treated dogs increased significantly after coronary occlusion and after reperfusion. These changes were greater in coronary venous blood than in femoral blood. Methionine administration (150 mg/kg, i.v.) before occlusion totally suppressed PMN activation, both after occlusion and reperfusion. CONCLUSIONS: PMN are promptly activated in myocardial ischemia, and methionine administration prevents such activation. However, methionine has no direct effect on spontaneous peroxidative activity, and f-MLP induced peroxidative activity. These in vivo effects of methionine, may additionally contribute to explain its protective role in experimental -788-877-7QQ8-8-7-88-8-8778--8Q78-----8--8-Q-7-Q7----- --------------8888 888888-7777777777777777777777777777777----------------888888888888888888 8877777--87--------8-----------------7-8888-887-----------8----8-8-87777 7777777------------------------------------------------------T7OW