Orotate,Citrate,and Urea Excretion in Rats Fed Various Levels of Arginine

Abstract

Summary

Thirty Sprague-Dawley male rats (50 g) were conditioned to an agar gel L-amino acid diet containing 1.12% arginine (Arg) before random assignment to diets containing different concentrations of Arg (1.12, 0.84, 0.56, 0.28 or 0%). Feed intake or N balance were depressed only with 0% Arg. Day 13 urinary excretions of citrate were 446, 1002, 2175, 3056 and 3655 μg for 1.12, 0.84, 0.56, 0.28 and 0.0% Arg, respectively. With Arg concentrations of 0.56% or lower urinary orotate was dramatically increased throughout the 13 day experiment. Urea excretion was greater than control with 0.56, 0.28 or 0% Arg. Within 48 hr on the 0.84% Arg diet, urea, ammonia and orotate excretion returned to control values but citrate remained above control. NH₄CI (3 mmoles) caused a doubling in ammonia excretion in all rats regardless of diet when compared to NaCl. Similarly, orotate excretion increased in all ammonia treated rats. Urea excretion was increased after NH4CI for rats fed 0.56, 0,84 or 1.12% Arg. We conclude that rapidly growing rats have limited reserves of Arg and that more than 0.84% dietary Arg was required to prevent abnormal loss of intermediary metabolites.