Combination treatment of parenteral arginine and nitric oxide inhibitor NG-nitro-L-arginine methyl ester in rats with peritonitis

Purpose: It has been shown that parenteral arginine may facilitate ureagenesis and improve leukocytic and splenocytic immunity and that the infusion of nitric oxide synthase inhibitor N-G-nitro-L-arginine methyl ester (L-NAME) may facilitate the production of arginine-associated amino acids in rats with subacute peritonitis. Herein, we investigated the effects of the combined treatment of parenteral arginine and L-NAME on arginine metabolism and inflammatory response. Methods and materials: Male Wistar rats underwent cecal puncture for induction of subacute peritonitis and were infused with conventional parenteral nutrition (arginine 0.95 g/kg/d) or parenteral nutrition supplemented with arginine (1.88 g/kg/d), L-NAME (25 mg/kg/d), or arginine plus L-NAME. Sham-operated and nonperitonitic rats with oral feeding (R group) or conventional parenteral nutrition (TPN group) were also included. Results: After 7 d of parenteral feeding, the L-NAME treatment significantly attenuated the peritonitis-induced reduction in body weight gain (1-way ANOVA, P < 0.05) and had a significant impact on decreasing body water percentage and on increasing body fat percentage and serum insulin concentrations (2-way ANOVA, P < 0.05). Parenteral arginine had a significant impact on increasing plasma arginine and ornithine and on decreasing serum glutamate oxaloacetate transaminase and plasma nitrite/nitrate in peritonitic rats. In addition, plasma interleukin-6 was significantly decreased by arginine and/or L-NAME treatment, and plasma prostaglandin E-2 was significantly decreased by arginine plus L-NAME treatment. Conclusion: These results suggest that the combination treatment of parenteral arginine and L-NAME may improve liver function and alleviate inflammatory response in rats with subacute peritonitis; however, it seems that parenteral arginine treatment is more beneficial than L-NAME. (C) 2013 Elsevier Inc. All rights reserved.