ARGININE ADMINISTRATION REDUCES HYDROGEN-PEROXIDE IN ISCHEMIA-REPERFUSION ENDOTHELIUM OF RATS

L-Arg as a precursor of nitric oxide (NO) can be used in experiments t o observe the action of NO. The present work is aimed at exploring the effect of oral administration of L-Arg on the ischemia-reperfusion (I R) damage of endothelial cells (EC) and the clearance of reaction oxyg en species in the IR carotid artery. Cerium-marked cytochemical techni que was used to localize the H2O2 product in endothelium. The area of Ce-H2O2 dense precipitate on the lumen surface of damaged endothelium per length of artery wall (nm(2)/nm) was measured. It was found that t he dense precipitate was decreased to 102.1+/-27.6 in rats drinking ta p water containing 2.5% L-arginine for 3 days. much less than in contr ol rats drinking tap water only (203.7+/-31.8, p<0.01). Furthermore. t he IR damage of EC was relieved markedly. Drinking tap water containin g D-Arg or L-Lys had no effects either on the amount of dense precipit ate or on the EC damage. N-G-nitro-L-arginine methyl ester. an inhibit or of NO synthase. decreased the effect of L-Arg markedly. These resul ts indicate that L-Arg administration can reduce H2O2 production in th e IR artery. and thus IR damage of EC is alleviated.