Interactions of diet and cortisone in the regulation of adaptive enzymes in rat liver.

The responses of the adaptive enzymes, serine dehydrase (L-serine hydro-lyase (deaminating), EC 4.2.1.13), ornithine transaminase (L-ornithine:2-oxoacid aminotransferase, EC 2.6.1.13), glucose 6-phosphate dehydrogenase (D-ghCOSe 6-phosphate:NADP oxidoreductase, EC 1.1.1.49), and glucokinase (ATP:o-glucose 6-phosphotransferase, EC 2.7.1.2), in rat liver were studied in relation to changes in the level of dietary protein and treatments with cortisone. The administration of cortisone markedly altered the responses of the enzymes to the diet, and the effects of the hormone depended both on the route of its administration (mtraperitonealor intramuscular injection) and on the dietary regimen of the rats. The response of each enzyme to the regulatory stimuli (diet and cortisone) showed elements of both uniqueness and similarity with respect to the responses of the other three enzymes to these stimuli. The results indicate that the regulatory system for each enzyme responds to a speCSC set of effecters (e.g. amino acids or carbohydrate or both, of dietary or endogenous origin) and that cortisone alters the capacity of the regulatory systems to interact with the appropriate eff ectors.