A note on the combined effects of exercise and food restriction on plasma enzyme activities in the rat.

Abstract

Plasma activities of malic dehydrogenase (MDH) and glutamic–pyruvic transaminase (GPT) were measured in adult male rats made to swim for 1 h either as a single, acute exercise or in repeated exercises (training) in the presence of a 50% food restriction. Food restriction per se elevated MDH and lowered GPT activities. Food-restricted rats responded to both acute exercise and training by an elevated plasma MDH activity. The effect of exercise on plasma MDH activity in these animals was greater than in rats fed ad libitum and was greater than could be accounted for by the summation of the individual effects of training and of food restriction. Plasma GPT activity was not altered by exercise in rats fed ad libitum or in food-restricted animals. It would appear, as suggested previously, that plasma MDH activity may be a useful biochemical criterion of training.