Abstract
Incubation of cardiac sarcolemma in the presence of dopamine β-hydroxylase (DBH), a catecholamine biosynthetic enzyme, increased β-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 α-receptors were unaffected under similar conditions. Since DBH is coreleased with norepinephrine, these results indicate that a functional coupling of the putative β-adrenergic receptor with DBH may exist in cardiac muscle.