Stimulatory effect of exogenous catecholamines on plasma HGH concentrations in presence of beta adrenergic blockade

The effect of infusions of epinephrine and propranolol singly and in combination on plasma growth hormone concentrations was determined in seven subjects. Epinephrine alone had no effect on plasma HGH concentrations. Propranolol which caused a rise in plasma HGH in only one subject when administered alone unmasked a stimulatory effect of epinephrine on plasma HGH concentrations when the two agents were given together. Analysis of plasma FFA supports the contention that the unmasking of a stimulatory effect of epinephrine on plasma HGH by propranolol was due to unopposed alpha receptor activity rather than suppression of epinephrine-induced FFA elevations. This investigation suggests that peripherally released or administered catecholamines may effect growth hormone secretory centers.