Amino acid

Biology

Ingestion

Arginine

Malic enzyme

Endocrinology

Glucagon

Biochemistry

Insulin

Enzyme inducer

Ornithine aminotransferase

Tyrosine aminotransferase

Glucokinase

Malate dehydrogenase

Enzyme

Dehydrogenase

Internal medicine

Hormone

Medicine

Chemistry

Ornithine

Biochimica et Biophysica Acta (BBA) - General Subjects

The ingestion of glucose ad libitum (for 19 h to 3 days) decreased the levels of enzymes concerned with amino acid metabolism in liver and intestine (but not in kidney and brain) and raised those of hepatic glucokinase, pyruvate kinase and NADP-malate dehydrogenase. Glucose feeding inhibited the substrate and cortisol induction of tryptophan oxygenase; it did not diminish the induction of tyrosine aminotransferase by glucagon (in adrenalectomized rats) or of renal ornithine aminotransferase by estrogen and it enhanced the response of NADP-malate dehydrogenase to thyroxine. In hepatomas, as opposed to normal liver, 24 h of glucose feeding increased the basal and the cortisol-induced levels of tyrosine aminotransferase. The results obtained with endocrinectomized and hormone-treated rats led to the following conclusions: (1) the effects of glucose ingestion on the quantitative pattern of hepatic enzymes is not mediated through altered secretion of pituitary, adrenal or pancreatic hormones but presumably by metabolites of glucose; (2) glucose, ingested in large amounts over 1–3 days, is not an inhibitor of enzyme inductions in general: its effect varies with the enzyme, the inducer and the tissue in which the enzyme is located.

The effect of glucose ingestion on basal and induced enzyme levels in rat tissues