Metabolism of arginine by the isolated perfused rat kidney

Abstract

In order to evaluate the renal contribution to the metabolism of arginine, we have evaluated its biosynthesis and catabolism in the isolated perfused rat kidney. The kidneys of eight male Sprague-Dawley rats were perfused with Krebs-Ringer-bicarbonate buffer containing albumin and amino acids. Twenty-five muCi of L-[guanidino-14C]arginine or 25 muCi L-[guanidino-14C]citrulline were added to the system and radiochromatograms of the perfusate were obtained at 0, 30, 60, and 90 min. Perfusate levels of urea, creatine, and guanidine derivatives were measured with high-pressure liquid chromatography. During perfusion there was net utilization of arginine and net production of creatine, guanidinoacetic acid (GAA) and guanidinosuccinic acid (GSA). The guanidino carbon of arginine was incorporated by the kidney into urea, creatine GSA, GAA, and guanidinobutyric acid. The production of 14C-labeled urea from L-[guanidino-14C]citrulline was substantially lower than that previously demonstrated in the liver, while that of arginine was approximately 20 times greater. These studies demonstrate the important contribution of the kidney to the synthesis and metabolism of arginine.

Production of Urea from Arginine in Pars recta and Collecting Duct of the Rat Kidney

“…Szepesi et al [2] and Rabinowitz et al [5] showed that arginase activity is predom inant in the renal medulla, whereas Rogers et al [3] found this activity mostly in the renal cortex. Two studies have shown that small amounts of urea are produced by the kidney either in vitro [9] or in vivo [10].…”

Distribution and metabolic fate of radioactive carbon from L-(U-14C)arginite administered into mice.

“…HPLC has been used for the analysis of arginine and its metabolites (15,19,20). The HPLC examination of the acid-soluble substances demonstrated that the distribution of radioactive acid-soluble substances depend on the organs and the intervals after injection.…”

“…The results by HPLC showed that urea and guanidinosuccinic acid were the principal metabolites in the organs examined. Guanidinosuccinic acid, has been detected in the liver of uremia rats (21) and in the liver and kidney of normal rats (19,20), is formed from transamidination of arginine to aspartic acid (20). On the other hand, the interorgan flow of arginine is an important issue in relation to the urea cycle and critical nature of the extrahepatic economy (4).…”

Characterization of the Renin-Angiotensin System in the Isolated Perfused Rat Kidney

“…Extracorporeal perfusion of the right kidney was performed according to a modification [18] of the procedure of NishiisutsufiUwo et al [16] and is summarized below. Donor animals were anesthetized with inactin (lOOmg/kg body weight, i.p.)…”