THE POOL SIZE, TURNOVER RATE, AND OXIDATION RATE OF BODY GLUCOSE IN ANESTHETIZED WARM- AND COLD-ACCLIMATED RATS EXPOSED TO A WARM ENVIRONMENT

Abstract

The size and space of the body glucose pool along with its turnover and oxidation rates have been measured in anesthetized 30[degree] and 6C acclimated rats by a method involving continuous intravenous injection of small amounts of D-glucose uniformly labelled with C14 and attainment of relatively constant specific activities of plasma glucose and respiratory CO2. Values of glucose pool space in warm-acclimated rats (essentially normal animals) were in accord with those found in the dog by a similar method. Results obtained on warm-acclimated rats indicated that previous published values of turnover and oxidation rates of glucose for normal rats were high by a factor of approximately 2 to 4. There was, however, close agreement between the values of turnover time of body glucose pool measured by the continuous infusion procedure and those obtained by others with the single intravenous or intraperitoneal injection procedure. In cold-acclimated rats, average absolute values of glucose pool size were significantly smaller than in warm-acclimated rats but the difference was lost when results were related to body weight. Small, non-significant differences in values of glucose pool size per 100 g body weight and in plasma glucose concentration combined to give a significantly larger glucose space in cold- than in warm-acclimated rats. Glucose turnover and oxidation rates, the ratio between these two quantities, and the proportion of respiratory CO2 derived from glucose oxidation were not significantly different in the two groups of rats, thus indicating that cold acclimation is not associated with major alterations in glucose metabolism at least when studied on fully fed anesthetized animals at 30[degree]C.