ROLE OF L-ARGININE IN PREVENTING MYOCARDIAL AND ENDOTHELIAL INJURY FOLLOWING ISCHAEMIA REPERFUSION IN THE RAT ISOLATED HEART/

The protective effect of L-arginine on ischaemia/reperfusion-induced m yocardial injury was investigated in the rat isolated Langendorff perf used heart. Six groups of hearts subjected to 30 min global ischaemia and 30 min reperfusion received either vehicle, D-arginine. L-arginine , the nitric oxide (NO)-donor S-Nitroso-N-Acetyl-D, L-Penicillamine (S NAP), the inhibitor of NO formation N-G-nitro-L-arginine (L-NNA), or L -arginine plus L-NNA. The recoveries of left ventricular double produc t and coronary flow at the end of reperfusion were significantly highe r in the L-arginine group (85 +/- 5 and 75 +/- 6%. respectively) than in the vehicle group (37 +/- 6 and 34 +/- 5%. respectively. P < 0.05). During both the ischaemic and reperfusion periods. left ventricular e nd diastolic pressure was lower in the L-arginine group than in the ve hicle group. Creatine kinase outflow and the area of no-reflow were sm aller in the L-arginine treated hearts (P < 0.01). There were no diffe rences between vehicle and D-arginine treated groups. L-NNA did not af fect recovery per se but abolished the protective actions of L-arginin e. SNAP produced the same protective effects as L-arginine. Acetylchol ine-induced endothelium-dependent vasodilation was reduced after ischa emia and reperfusion in the vehicle group but not in the L-arginine gr oup. It is concluded that L-arginine reduces ischaemia/reperfusion-ind uced myocardial and endothelial injury. The results suggest that the b eneficial effects of L-arginine are related to preserved synthesis and release of NO.