The effects of starvation, environmental temperature and injury on the rate of disposal of glucose by the rat

Abstract

1. The disposal rate of glucose, R, given by R=kvQ, where Q is the quantity of plasma glucose and kv is a rate coefficient, was determined from the disappearance of [U-14C]-glucose from blood after single intravenous injection. Values of R should be close to the carbohydrate oxidation rate in the states investigated. 2. Normal rats (i) experimental methodology was studied. The best (single sampling) method gave the following results. (ii) The plasma glucose concentration (Cp) and R were temporarily increased by the stress of handling and injection. (iii) R was increased by decreasing the environmental temperature from 29°C to 20°C in line with previously published (Stoner & Marshall, 1971) changes in total body O2 consumption. (iv) Starvation decreased R such that R=constant×Cp2. (v) The results suggested some central control of cell permeability to glucose. 3. Injured post-absorptive rats were studied in the ebb phase after three severe injuries: scalding at 20° and 29°C (non-lethal) and bilateral hind-limb ischaemia at 20°C (85% mortality). (i) Handling and injection did not affect Cp. (ii) The rise in Cp after injury was not closely correlated with its severity. (iii) The value of R was nearly independent of severity. (iv) Unlike in normal rats R varied little with ambient temperature (in line with O2 consumption) or with Cp. Values of kv varied inversely as Cp. (v) The results were explained in terms of a centrally integrated response to injury involving the hypothalamus which over-rode the controls operating in normal rats. Hormonal factors are discussed.