Modulation of cardiac beta-adrenergic receptors by dopamine beta-hydroxylase.

Incubation of cardiac sarcolemma in the presence of dopamine beta-hydroxylase (DBH), a catecholamine biosynthetic enzyme, increased beta-adrenergic receptor density by 68% as measured by [3H]dihydroalprenolol (DHA) binding. The addition of DBH to plasma membranes isolated from brain, kidney, skeletal muscle, liver and intestine did not alter [3H]DHA binding. Cardiac alpha-receptors were unaffected under similar conditions. Since DBH is coreleased with norepinephrine, these results indicate that a functional coupling of the putative beta-adrenergic receptor with DBH may exist in cardiac muscle.