Effects of adrenaline on the dynamics of carbohydrate metabolism in rats treated chronically with adrenaline.

Abstract

Following a subcutaneous injection of adrenaline (300 mug/kg), blood-glucose levels were lower in rats treated chronically with adrenaline (300 mug/kg twice a day for 28 days) than in control rats during at least 2.5 h after the injection. To explain this difference of response, the turnover rate of glucose was measured in control and adrenaline-treated rats during adrenaline infusion (0.75 mug/kg- minus 1 min- minus 1), with [U- minus 14C]glucose as tracer. It was found that the rate of appearance of glucose was greater in the control than in the adrenaline-treated group after a 120-min infusion of adrenaline. The rate of disappearance of glucose in the treated rats increased during the first 60 min of infusion and stayed at this elevated level for a subsequent 2 h, whereas in the control rats, it remained unchanged at the beginning of adrenaline infusion and significantly increased only during the second and third hours of infusion. In addition, the metabolic- clearance rate of glucose was not modified by adrenaline in the treated group, but in the control group, the initial clearance rate was significantly less than in the treated group, and decreased during the first hour of adrenaline infusion even though blood glucose reached values of 244 mg/100 ml. ,rom these data, it is suggested that rats adapt to a chronic exogenous supply of adrenaline by a reduced increase in glucose production in response to adrenaline infusion and a better glucose utilization, which possibly indicates a decrease in the inhibitory effect of adrenaline on insulin secretion.