Insulin and glucagon during pentobarbitone anaesthesia.

The induction of sodium pentobarbitone anaesthesia (45 mg/kg, ip) in 18 hour fasted mice produced a mild transient hyperglycaemia and a small but persistent increase in plasma glucagon concentrations. Plasma insulin concentrations became raised as the period of anaesthesia progressed. Plasma glucagon concentrations remained elevated as consciousness was regained, and a second episode of mile hyperglycaemia was observed at this time. Plasma free fatty acid concentrations were not altered by the anaesthesia and all parameters had returned to control values four hours after consciousness was regained. During anaesthesia glucose tolerance was impaired and the plasma insulin response to glucose and glucagon was enhanced. Higher plasma glucose and insulin concentrations were also observed after glucagon administration, and insulin hypoglycaemia tests revealed a decrease in the rate of glucose disappearance during anaesthesia. Four hours after consciousness was regained all these responses had returned to control values, except glucose tolerance which improved in comparison with controls. These results indicate that impaired glucose homeostasis during pentobarbitone anaesthesia is dependent on changes in both the secretion and physiological effects of insulin and glucagon.