Effect of temperature on metabolism of glucose in vitro

Abstract

We recently showed that hypothermic rats fail to remove glucose from the extracellular phase. This information led to these studies on the uptake of glucose at low temperatures by rat diaphragm and red blood cells and its phosphorylation by hexokinase. It is shown here that rat diaphragm and red blood cells utilize glucose at all temperatures from 1 to 38 C. Both processes follow the Arrhenius equation and give µ equal to 18,000 and 21,900, respectively. The velocities of the phosphorylation of glucose by hexokinase from yeast and from rat muscle both yield straight lines on an Arrhenius plot with µ equal to 13,300 and 14,900. The temperature coefficient of the velocity of action of hexokinase is consistent with the effects of temperature on other enzymes. Penetration of glucose into cells at low temperatures apparently equals or exceeds the rate of phosphorylation. Thus the abnormal metabolism of glucose in hypothermia is not caused by failure of glucose to penetrate cells, and there is no unusual sensitivity of hexokinase to changes in temperature.