Effect of arginine, urea and .ALPHA.-aminoisobutyric acid on the urinary nitrogen excretion in adult chicks.

Abstract

The relations among urinary excretion of dietary urea, metabolic one derived from arginine degradation and arginine and the effects of α-aminoisobutyric acid (AIB) on these relationships were studied using adult chicks with an artificial anus. In chicks fed the basal diet containing a normal amount of arginine, the urinary excretion of arginine was negligible. On the day when chicks were fed the excess arginine (2%) diet, urinary excretion of urea and arginine was highly increased. The excess feeding of arginine for the AIB-treated chicks further increased the excretion of urinary arginine and undetermined nitrogen, but the urea excretion was significantly lower than that of the excess arginine chicks. In chicks fed the 1% urea diet with or without AIB, a significantly higher excretion of urea and undetermined nitrogen was observed than those in the control chicks.These results showed that AIB has the following functions for arginine and urea excretion in chicks. (1) AIB supplemented to the excess arginine diet decreases the urea formation through suppression for kidney arginase activity. (2) AIB promotes the urinary excretion of excess dietary arginine by means of a depression of renal reabsorption of this amino acid. (3) When AIB is added to the 1% urea diet, this material gives no effect on urinary excretion of urea.