Effects of fasting and glucose ingestion on the retention of ammonia.

Sprinson and Rittenberg,’ in their studies of the effects of diet on the retention of ammonia, were led to conclude that ammonia is extensively utilized for protein synthesis only when there is a deficiency of dietary amino acids. For some time this laboratory has been engaged in a study of the influence of glucose on the metabolism of amino acids and proteins. The results so far obtained indicate that glucose causes a marked repression of amino acid catabolism.2 These results led us to investigate the effects of glucose on the retention of ammonia, and the present communication reports the results of these studies. It was found that the retention of administered W5-ammonia was considerably less in fasting animals than in those fed glucose. Thus the conclusion that extensive utilization of ammonia occurs only when there is a deficiency of dietary amino acids does not appear to be entirely correct. Rather, the extensive retention of ammonia on a protein-poor diet, such as was used in the experiments described by Sprinson and Rittenberg, may at least in part be ascribed to the effects of the high carbohydrate content of the diet.