Effect of Zinc Deficiency on Urinary Excretion of Nitrogenous Compounds and Liver Amino Acid-catabolizing Enzymes in Rats

Abstract

The effect of dietary zinc deficiency in rats on the levels of urinary nitrogen, urea, uric acid, and creatinine was studied. Zinc deficiency substantially increased urinary excretion of total nitrogen. The amount of urea excretion of zinc-deficient rats was approximately 42 and 87% more than that of zinc-supplemented pair-fed and ad libitum-fed rats, respectively. Zinc-deficient rats also showed significantly higher excretion of uric acid. No difference was observed in creatinine excretion between zinc-deficient and zinc-supplemented groups. Further studies demonstrated that zinc-deficient rats had increased activities of liver tryptophan pyrrolase and arginase. The activities of liver threonine dehydratase and serine dehydratase were unaffected by zinc deficiency. Overall findings support in principle the concept that zinc deficiency results in an increased protein catabolism and also indicate that the hepatic amino aciddegrading enzymes may be one of the possible regulating sites involved in the protein metabolism of rats.