Effect of adrenergic blockade on glucagon and growth hormone secretion in normal and diabetic children.

Studies were conducted in four normal and six diabetic children to assess the role of adrenergic blockade on basal and arginine-stimulated growth hormone and glucagon secreation. Each subject had, on three separate occasions, infusion of arginine alone or in conjunction with alpha (phentolamine) or beta (propranolol) adrenergic blockade. Clinically, there was evidence of adequate blockade by each agent. Basal hormone growth levels were not significantly different in the two groups (1.3 +/- 0.2 to 2.1 +/- 1.0 ng/ml in normal subjects; 3.0 +/- 1.1 to 6.0 +/- 3.1 ng/ml in diabetics (mean +/- 1 SEM)) but the peak growth hormone after arginine was significantly greater in the diabetic children than control subjects (34.3 +/- 7.2 versus 12.3 +/- 3.1); in both groups alpha-blockade suppressed the growth hormone response, whereas beta-blockade had no significant effect. Basal glucagon concentrations were similar in both groups (147 +/- 31 to 214 +/- 21 pg/ml in normal subjects; 100 +/- 20 to 124 +/- 17 pg/ml in diabetics on three different occasions) despite the coexistent hyperglycemia of the diabetics. Neither basal nor maximally stimulated glucagon secretion was significantly affected by alpha or beta blockade in the juvenile diabetic or control children. The results suggest that sympathetic overactivity via alpha receptors may contribute to the hypersecretion of growth hormone in juvenile diabetes and that the alpha or beta adrenergic receptor alone does not appear to modulate basal or arginine stimulated glucagon secretion.