Binding of (3H)dihydroalprenolol to beta adrenoceptors of cells isolated from adult rat heart.

Myocardial cells isolated from adult rat heart bind (3H)dihydroalprenolol. Sixty-one percent of this binding appeared to be at the beta adrenoceptors since it was inhibited by saturating quantities of the beta antagonist propranolol or by the beta agonist isoprenaline. The binding is stereoselective as the l-isomer of isoprenaline caused greater inhibition than the d-isomer. The binding of (3H)dihydroalprenolol to beta adrenoceptors was saturable; half maximum binding occurred at about 8 nM and full saturation at 30--40nM.