CLASSIFICATION OF ALPHA(1)-ADRENOCEPTOR SUBTYPES

Two alpha(1)-adrenoceptor subtypes (alpha(1A) and alpha(1B)) have been detected in various tissues by pharmacological techniques, and three distinct cDNAs encoding alpha(1)-adrenoceptor subtypes have been clone d. The profile of an increasing number of subtype-selective compounds at cloned and endogenous receptors recently has facilitated alignment between cloned and pharmacologically defined alpha(1)-adrenoceptor sub types. Thus, alpha(1a)-adrenoceptors (previously designated alpha(1c)) , alpha(1b)-adrenoceptors and alpha(1a)-adrenoceptors (previously desi gnated alpha(1a), alpha(1d) or alpha(1a/d)) are now recognized. Since the alpha(1d)-adrenoceptor shares characteristics with both alpha(1A)- and alpha(1B)-adrenoceptors, tissues previously reported to express a lpha(1A)- and/or alpha(1B)-adrenoceptors may additionally contain alph a(1d)-adrenoceptors. This article reviews the features of all three su btypes and discusses possible pitfalls in their pharmacological identi fication.