The metabolic consequences of adrenergic blockade: a reveiw

The effects in man of adrenergic blocking agents on plasma insulin, glucagon, growth hormone, and lipid metabolism are reviewed. Whereas basal insulin may be slightly inhibited by beta- and enhanced by alpha-adrenergic blockade, more marked suppression may be achieved under circumstances of high exogenous or endogenous catecholamine stimulation. The relative effects of beta1 or combined beta 1 and beta2 blockers in man are unknown. Glucagon release is probably provoked by beta- and inhibited by alpha-stimulation in man. Muscle glycogenolysis is inhibited by propranolol, and under situations of hepatic glycogen depletion, clinical hypopglycemia may occur. This may also account for the failure of significant hyperglycemia to be observed in short-term experiments on fasting subjects in whom insulin release may be suppressed and glucagon release enhanced. Growth-hormone release is enhanced by beta-adrenergic blockade. Free fatty acid formation in vivo is inhibited by intravenous beta blockade, but the effects of oral administration on triglyceride production and lipoprotein profiles remain uncertain. The inter-relationships between the effects of adrenergic blockade at different sites of hormone and substrate release are unclear but may have important consequences in alteration in carbohydrate tolerance and lipid metabolism. The relative effects of beta-blocking drugs with differing specificity must be determined.