Effects of dietary protein contents and habitual endurance exercise on supplemental leucine oxidation in mice

Abstract

ABSTRACT The effects of dietary protein contents and regular exercise on the oxidation of supplemented leucine were examined. In the short-term study, male BALB/cCrSlc mice were fed diets containing 0, 10, 20, 35, and 60% protein: energy ratios for 1 week. In the long-term study, exercised and sedentary mice were fed diets containing 20, 35, and 60% protein ratios for 9 weeks. After the feeding periods, the mice were a bolus administered oral supplements of l-[1-13C] leucine. Expired gas was analyzed, and oxidized leucine was expressed as a relative 13CO2/12CO2 ratio. In the short-term study, the peak 13CO2/12CO2 ratio significantly increased with diet protein concentrations. Moreover, the long-term study also showed that the peak 13CO2/12CO2 ratio was significantly increased by high protein diets in both exercised and sedentary mice. Our results indicate that supplemental leucine oxidation is associated with consumption of a high-protein diet, irrespective of exercise status. Abbreviations: AUC: area under the curve; EX: exercise; RQ: respiratory quotient; SED: sedentary; VO2/W: oxygen uptake per body weight