Role of glucagon in the hyperglycemic response to catecholamines in fasted baboons

The hyperglycemic activities of epinephrine (EP1) and isoproterenol (ISO) in baboons correlated with their ability to increase plasma glucagon (1RG) levels relative to insulin (1R1). EPI inhibited IRI release and produced greater increases in plasma glucose and IRG than did ISO. ISO increased plasma IRI levels more than IRG. Infusion of somatostatin blocked IRG release and inhibited hyperglycemic responses to EPI by approximately 50%. These findings indicate that, as in man, IRG release contributes significantly to the hyperglycemic effects of catecholamines in baboons. The baboon thus appears to be a suitable model for predicting effects of drugs on glucose homeostasis in humans.