Effects of L-arginine on LPS-induced lung mitochondrial injury in rats

Objective To evaluate the effects of L-aronine(L-Arg) on LPS-induced lung mitochondrial injury in rats.Methods Twenty.four male SD rats weighing 230-270 g were randomly divided into 3 groups(n=8 each):groupⅠsham operation(S);group ⅡLPS and group Ⅲ LPS+L-Arg.LPS 5 mg/kg in normal saline(NS)1 ml/kg waft given iv in group Ⅱ and Ⅲ while in group Ⅰ NS 1 ml/kg was given iv instead of LPS. L-Arg 500 ms/kg in NS 1 ml/kg was given intrapefitoneally(IP)at 3 h after LPS administration in group Ⅲ,while in group Ⅰ I and Ⅱ NS1 ml/kg was injected IP instead of L-Arg.The animals were sacrificed at 3 h after L-Arg injection by exsanguination and the lungs were immediately removed.The mitochondrias of the lungs were isolated by differentia centrifugation.The activities of SOD,GSH-Px,ATPase,inducible,constitutive and total nitric oxide synthase(iNOS,cNOS,NOS)and MDA and NO contents,the degree of mitochondrial swelling,mitocho-ndrial activity and membrBne fluidity of mitochondria wefe measured.Ultrastructure of cells in lung was examined wlth eleciron microscope.Results The SOD,GSH-Px.ATPase and mitochondriai activities and the membrane fluidity of mitochondria were significantly decreased,while the MDA and NO contents and iNOS,NOS activities and the degree of mitochondriM swelling in the lung were significantly increased in group LPS as compared with group S.The lung cytoplasm and mitoehondria swelled,the cfistae were disrupted,dissolved or disappeared in LPS group(Ⅱ).The LPS-induced changes were ameliorated by L-Arg in group Ⅲ as compared with group Ⅱ.Conclusion L-Arg can attenuate lung mitochondrinl injury induced by LPS by enhancing antioxidative effects. Key words: Arginine; Endotoxemia; Lung; Mitochondria