INCREASED NUMBER OF BETA-ADRENERGIC RECEPTORS IN THE HYPERTROPHIED MYOCARDIUM

Development of cardiac hypertrophy is associated with depletion of endogenous catecholamine stores and increased inotropic response to exogenous catecholamines. A biochemical basis for these changes is provided by the observation that the number of cardiac β-adrenergic receptors-as reflected in specific [3H]dihydroalprenolol binding-is increased in hypertrophy without a change in the affinity of dihydroalprenolol for the binding sites or in the capacity of isoproterenol to displace dihydroalprenolol. This change in β-receptor numbers may be an important adaptive mechanism for preserving the contractile performance of the hypertrophied myocardium. © 1979.