Effects of Burn Injury on Insulin Secretion and on Sensitivity to Insulin in the Rat in vivo

Abstract. Both insulin resistance and impairment of insulin secretion are know to occur in man after injury. The relative importance of these effects was studied in rats 2 h after a non-lethal 20 % dorsal scald. No impairment of insulin secretion was found after this injury. Concentrations of both blood glucose and plasma insulin were elevated in scalded rats. Scalded rats responded to intravenous glucose injection (1. 0 g/kg) with a further rise in plasma insulin concentration, which remained normal for the prevailing blood glucose concentration. However, marked impairment of glucose tolerance was observed, indicating the presence of insulin resistance. After intravenous insulin injection (1. 0 U/kg) the initial rate coefficient for fall of blood glucose concentration was significantly lower (p < 0–02) in scalded (mean 3. 9 % min. ^-1) than in control rats (mean 6–3 % min. ^-1). The minimum in blood glucose concentration after insulin injection was reached at 10 min. in control rats, but not until 60 min. after injection in scalded rats. This difference was due to a delay in compensation for the hypoglycaemia in the scalded rats, since the rate of disappearance of insulin measured by injection of a tracer of 25i-labelled bovine insulin was not decreased after this injury. It was concluded that the impairment of glucose utilization in scalded rats (Heath and Corney, 1973) is due to decreased sensitivity to insulin rather than to suppression of insulin release.