Protective effect of antioxidants on blood oxidative stress caused by arginine.

In this study, we investigated in vivo and in vitro effect of arginine on parameters of oxidative stress namely thiobarbituric acid-reactive substances (TBA-RS) and total radical-trapping antioxidant parameter (TRAP) in plasma and on the antioxidant enzymes activities catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) in erythrocytes of rats. Results showed that acute administration reduced TRAP and CAT activity and increased TBA-RS. Furthermore, in vitro studies did not alter oxidative parameters studied. The influence of N(ω)-nitro-L-arginine methyl ester (L-NAME) and antioxidants (α-tocopherol plus ascorbic acid) on the effects elicited by arginine was also studied. In addition, simultaneous injection of L-NAME or treatment with antioxidants prevented the alteration on TRAP, TBA-RS, and CAT activity caused by arginine. Data indicate that oxidative stress induction is probably mediated by the generation of NO and/or ONOO(-) and other free radicals, because L-NAME and these antioxidants prevented these effects caused by arginine.