Effect of L-arginine on pulmonary injury induced by ischemia reperfusion in rabbits and mechanism

Objective To study the effect of L-arginine on the ischemia-reperfusion(I/R) injury of lung in rabbits and it's mechanism.Methods Thirty male Japanese white rabbits were divided into three groups randomly.(1)I/R control group(group C): left hilus was clamped for 60 minutes,then reperfused for 60 minutes; (2)L-Arginine group(group LA): 100mg/kg L-Arginine was intravenously injected,then left lung was clamped and reperfused as group C after 20 minutes;(3) LArginine + methylene blue group(group ML): 0.4ml/kg 1%methylene blue was intravenously injected,then next steps were done like group LA after 20 minutes.The levels of nitric oxide(NO) and cyclic GMP(cGMP),and the activities of nitric oxide synthase(NOS) were detected individually,the ratio of wet to dry of lung tissue weight(W/D) was calculated;electron microscopic evaluation were also done on rabbit lung tissue.Results Compared with pre-ischemia,the contents of NO at the time of either end-ischemia or end-reperfusion apparently increased in group LA(P(0.01)) and group ML(P0.01),while those didn't apparently change in group C.In group LA,the contents of cGMP increased and the values of W/D more decreased than those in group C(P0.05) and group ML(P0.05).The activities of TNOS or cNOS were obviously higher in group LA and group ML than those in group C(P0.05).The ultrastructural analysis of the lung tissues showed that the mitochondrias in microartery endotheliocytes and Ⅱ type alveolar epithelial cell were swollen or vesicular and plenty of PMNs stayed in capillary chambers in group C and ML,especially severe in group C,while the microartery endotheliocytes in group LA were nearly normal.Conclusion L-arginine can prevent the ischemia reperfusion injury in rabbit lung by regulating the pathway of NO/cGMP.