Amino acid profile and nitric oxide pathway in patients on continuous ambulatory peritoneal dialysis: L-arginine depletion in acute peritonitis.

To gain insights into the amino acid metabolism and L-arginine-nitric oxide system, we studied 21 control continuous peritoneal dialysis (CPD) patients and 13 patients with 15 episodes of acute peritonitis. The concentrations of amino acids, including L-arginine, were measured in the peritoneal dialysate and in the serum. The data demonstrate that patients with end-stage renal disease on CPD who have acute peritonitis develop L-arginine deficiency. The majority of patients with acute bacterial peritonitis have increased nitric oxide production as judged by the level of nitrites in the dialysate. The recovery from peritonitis is associated with a decline in nitric oxide generation. Paradoxically, there is a smaller subgroup of these patients that shows low nitrite levels during acute peritonitis. The nitrite to L-arginine ratio in the peritoneal dialysate is increased in patients with peritonitis, further suggesting the development of substrate deficiency. These findings implicate L-arginine as a conditionally essential amino acid in CPD patients with acute peritonitis and raise questions concerning the necessity of L-arginine supplementation.