A decreased hyperglycemic response to adrenaline after prolonged, exhausting exercise in dogs

The aim of the investigations carried out on dogs was to elucidate possible causes of the decreased hyperglycemic response to adrenaline after exhausting exercise. The k-values of i.v. glucose tolerance tests were calculated and the dose-response relationship to infused adrenaline was analyzed under control, resting conditions, and after exhausting exercise. K-values (KG-exc.) were significantly higher (p less than 0.01) after exercise than in control experiments, whereas hyperglycemic responses to the applied doses of adrenaline: 0.25, 0.5, 1.0, 2.0 and 3.0 mug-kg-1min-1 were considerably lower. In both situations a linear relationship was found between the hyperglycemic response and the dose of adrenaline, although the slope of the regression line, expressing this relationship, was significantly lower after exercise than that under control conditions. It is suggested that the decreased hyperglycemic response to adrenaline after prolonged, exhausting exercise may be attributed to both the increased rate of glucose elimination from blood, and a decreased responsiveness of the liver to adrenaline.