Effects of drugs on beta-adrenergic receptors on human lymphocytes

The density of beta-adrenergic receptors has been determined on membranes prepared from lymphocytes of normal human volunteers. Long-term administration of propranolol resulted in an increase in the density of receptors, whereas administration of the agonists ephedrine and terbutaline elicited a marked decrease in the density of receptors. These changes may explain the delayed side effects observed when propranolol administration is abruptly discontinued and the decreased efficacy that occurs during long-term administration of an agonist. In other experiments, pindolol, an antagonist with intrinsic sympathomimetic activity, was administered to normal subjects. A marked decrease in the density of receptors occurred within 1 day of administering pindolol. This effect persisted beyond the time at which pindolol administration was discontinued.