Enhanced ketone body uptake by perfused skeletal muscle in trained rats

Training effect on exercise-induced hyperketonemia was investigated in normal post-absorptive rats subjected to running exercise on a treadmill. Furthermore, rat hindlimb-muscle perfusion was performed to elucidate the mechanism of the training effect. A medium intensity prolonged exercise (running at 15 m/min for 90 min) caused a greater increase in plasma 3-hydroxybutyrate than in acetoacetate both during and after the exercise. Training with medium-intensity exercise (15 m/min) for 90 min 3 times per week for 14 wks or 28 wks caused 1) a reduction of the increase in plasma ketone body (mainly 3-hydroxybutyrate), free fatty acids and glucagon induced by the exercise, and 2) an increase in ketone body (mainly acetoacetate) uptake by perfused skeletal muscle. The present study demonstrates that the reduction of exercise-induced hyperketonemia by prolonged training is caused by increased ketone body utilization in skeletal muscle, and suggested that inhibition of hepatic ketogenesis might also participate in this reduction.