Acebutolol-induced decrease of mononuclear leukocyte beta-adrenoceptors in hypertension

The regulatory action exerted on receptors by acebutolol, a cardioselective beta-blocker containing intrinsic sympathomimetic activity, has been investigated. beta-Adrenoceptor affinity and density of human mononuclear leukocytes were assayed in hypertensive patients before and after treatment with 400 mg/day acebutolol. While receptor affinity showed no changes between pre- and post-treatment values, a statistically significant decrease has been demonstrated in receptor density following treatment. Blood pressure and heart rate were also measured in order to test the efficacy of the administered drug. All these parameters showed a fall in the post-treatment values. It is concluded that the partial agonist acebutolol, in spite of the fact that it acts clinically as a beta-blocker, has the regulatory mechanism characteristic of agonists.