Hypoglycemic responses to insulin in normothermic and hyperthermic young dogs.

The present study was conducted in 10 healthy young dogs in which pattern of hypoglycemia to injected insulin (0.12 U/kg I.V.) was studied at normothermic (38.5 degrees C) and hyperthermic (42.5 degrees C) body temperatures. Average maximum fall in plasma glucose concentration from the control level was 44.3% and 53.8% in normothermic and hyperthermic dogs respectively. The hypoglycemic response to injected insulin was much greater and prolonged in hyperthermic dogs. The recovery of plasma glucose to preinjection level was also very sluggish and incomplete in these dogs. The above changes in hyperthermic animals may be due to enhanced secretion of insulin, as well as an increased sensitivity to injected insulin. The slow recovery of plasma glucose to preinjection level following insulin administration in hyperthermic dogs would indicate inefficient feedback mechanisms which normally operate to raise the plasma glucose during hypoglycemia.