Role of Kidney Arginase in Variations of the Arginine Requirement of Chicks

Abstract

A study was conducted to assess the role of kidney arginase activity in variations of the arginine requirement of chicks. Kidney arginase activity and urea excretion were measured in chicks for which the arginine requirement was altered by the feeding of amino acid excesses or by genetic selection. Marked increases in arginase activity and urea excretion were associated with increases in the arginine requirement. Time-course studies revealed that the initial increases in kidney arginase activity and urea excretion corresponded in time with the initial decreases in rate of growth and food intake when chicks were fed arginine-limiting diets. The feeding of α-aminoisobutyric acid, α-amino-δ-hydroxyvaleric acid, glycine and threonine depressed the kidney arginase activity and urea excretion of chicks fed arginine-limiting diets, and resulted in improved gain and efficiency of feed utilization. Kidney arginase was found to be readily altered by a variety of dietary amino acids when arginine content of the diet was limiting for growth. It is proposed that the alteration of the activity of this enzyme is a major factor in variations of the arginine requirement of chicks.