Effect of indenolol treatment on beta-adrenergic receptors of polymorphonucleates in essential hypertension.

Indenolol is a new antihypertensive agent, whose beta 1-adrenoceptor antagonist properties combined with beta 2-adrenoceptor agonist properties have been shown by experimental studies in animals. Our previous work reported that in vivo beta-adrenoceptor blocking drugs markedly increase the beta-adrenoceptor (BAR) number, without increasing BAR affinity. The aim of this study was to evaluate BAR density and affinity before and after indenolol therapy in membranes of polymorphonucleates (PMN) of patients with essential hypertension. Polymorphonuclear binding parameters were studied in 12 hypertensives (WHO stages I and II) after 14 days of placebo and after 21 days of indenolol therapy (120 mg once daily orally). Indenolol did not increase BAR number but significantly decreased (P less than 0.01) BAR affinity. On the basis of these data it is concluded that indenolol does not induce the same changes in PMN's BAR as previously observed with oxprenolol, propranolol and labetalol. This phenomenon may account for the absence of rebound effect after withdrawal of indenolol in hypertensives.