TISSUE ENZYME RESPONSE TO COLD AND TO HYPERPHAGIA IN THE RAT

Abstract

In rats exposed to cold (5 °C) for 14 days the activities of liver arginase, alanine-transaminase, and glucose-6-phosphatase and of kidney phosphate-activated glutaminase were increased. In animals with a comparable hyperphagia due to bilateral ablation of the ventromedial region of the hypothalamus there was a smaller although significant increase in activity of kidney glutaminase but, in contrast to the effect of cold exposure, there was a significant decrease of liver alanine-transaminase activity and no apparent effect upon the activities of liver arginase or glucose-6-phosphatase. It is concluded that changes of enzyme activities in cold-exposed rats are not simply an adaptation to the increased nutrient flow consequent upon the hyperphagia induced.