Regeneration of beta-adrenergic receptors in senescent rats: a study using an irreversible binding antagonist.

Abstract

Bromoacetylalprenololmenthane binds and blocks irreversibly .beta.-adrenergic receptors. The drug was bound to membranes prepared from hearts, lungs and brains of both senescent and young rats with a similar affinity. When this drug was injected into rats in nontoxic doses (up to 70 mg/kg), up to 90% of .beta.-adrenergic receptors were irreversibly blocked 4 h after injection, whereas the injection of similar amounts of (.+-.)-alprenolol was without effect on receptor number. In senescent animals this blockade lasted considerably longer than in young animals; receptor numbers in hearts and lungs of senescent rats returned to control levels only 1 mo. after injection. The number of .beta.-adrenergic receptors in brains of senescent rats was unaffected by this drug. Based upon the long-lasting blockade of .beta.-adrenergic receptors in therapeutically important organs, it appears that irreversible binding blockers may have potential in the treatments of senescent organisms. [.beta.-Adrenergic antagonists continue to be one of the main medications used to treat hypertension.].