Objective: To study the protective effect of NO precursor
L arginine (L arg) on myocardium in rats with acute myocardial
ischemia and its mechanism. Methods:A rat model of
acute myocardial ischemia induced by pituitrin (Pit) was applied. 30 Wistar rats were divided into three groups : normal control group (injected with saline),positive control group (injected with 30 u/kg of Pit),and L arg treatment group (Pit injection followed by L arg injection). The expressions of L selectin on neutrophils and P selectin on myocardial microvascular endotheliocytes were determined. The myocardial infarct area,number of neutrophil infiltration and the levels of NO and MDA in plasma were determined. Results: In the positive control group (Pit group),the expressions of L and P selectin,the number of neutrophil infiltration and the serum MDA increased,while the serum NO level decreased when compared with the normal control group. In the L arg treatment group,the changes of these indicators were significantly lesser than those in the Pit group ( P <0.01),and the infarct area was smaller as well. Conclusion: The results suggested that L arg exerted significant cardioprotective effects in acute myocardial ischemia,and there was a positive correlation between the cardioprotection of L arg and the inhibition of NO on selectins expression.