Alterations in glucose kinetics induced by pentobarbital anesthesia.

Because pentobarbital is often used in investigations related to carbohydrate metabolism, the in vivo effect of this drug on glucose homeostasis was studied. Glucose kinetics, assessed by the constant intravenous infusion of [6-3H]- and [U-14C]glucose, were determined in three groups of catheterized fasted rats: conscious, anesthetized and body temperature maintained, and anesthetized but body temperature not maintained. After induction of anesthesia, marked hypothermia (5 degrees C decrease in core temperature) developed in rats not provided with external heat. Anesthetized rats that developed hypothermia showed a decrease in mean arterial blood pressure (25%) and heart rate (40%), whereas no differences were seen in blood pressure and heart rate of conscious and euthermic anesthetized rats. Likewise, the plasma lactate concentration and the rates of glucose appearance, recycling, and metabolic clearance were reduced by 30-50% in the hypothermic anesthetized rats. Changes in whole-body carbohydrate metabolism were prevented when body temperature was maintained. Because plasma pentobarbital levels were similar between the euthermic and hypothermic rats during the first 2 h of the experiment, the rapid reduction in glucose metabolism in this latter group appears related to the decrease in body temperature. The continuous infusion of epinephrine produced alterations in glucose kinetics that were not different between conscious animals and anesthetized rats with body temperature maintained. However, marked differences were seen in hypothermic rats. Thus pentobarbital-anesthetized rats became hypothermic when kept at room temperature and exhibited marked decreases in glucose metabolism. Such changes were absent when body temperature was maintained during anesthesia.