Diurnal Response in Endogenous Amino Acid Oxidation and Degradation of Body Protein of Meal-Fed Rats

摘要

A model has been developed to measure the effects of dietary protein on daily fluctuations in the rate of endogenous amino acid oxidation and degradation of body protein in meal-fed and starved rats. In addition, N-methylhistidine and hydroxyproline were utilized to estimate changes in the rate of degradation of myofibrillar and collagen proteins. In rats meal-fed a normal diet of 18% casein, a diurnal response was observed in rate of oxidation of radioactive amino acids contained in endogenous labelled body protein, with a nadir 16-20 h and maximum 24 h after beginning the feeding. This observation apparently is related to alterations in rates of protein degradation and flux of amino acids from nonhepatic tissues to site of oxidation in liver.