Effects of acute heat stress on tissue carbohydrate in fasted rats

Exposure of starved female rats to 45 degrees C db, 26 degrees C wb for 0.25-2 h tended to lower blood glucose levels, and increase blood lactate levels, compared with controls at 24 degrees C db, 14 degrees C wb. There was a sustained liver glycogenolysis, but no detectable change in muscle glycogen level. Despite the severity of the stress, the effect of a high environmental temperature on carbohydrate metabolism cannot be satisfactorily interpreted in terms of increased adrenal medullary activity. It is suggested that increased respiratory muscle activity may explain the changes observed.