Abstract
Summary
The amplitude of the 24-hr rhythm in hepatic tyrosine transaminase activities of rats fed hourly was markedly reduced when compared to the activities of the enzyme in rats eating ad libitum. Reversing the lighting schedule reversed the rhythms but did not change their amplitudes. The TT rhythm of adrenalectomized rats eating ad libitum was reduced in amplitude and the rhythm extinguished in animals fed hourly. Hourly feedings did not influence the cyclicity of the corticosterone content of the adrenal. It is concluded that rhythms in food ingestion and adrenal cortical secretions play roles in the generation of the rhythmicity of hepatic tyrosine transaminase activities but that the diurnal variation in adrenal corticosterone content is not related to the cyclicity of food intake.
Get full access to this article
View all access options for this article.