CHARACTERIZATION OF ALPHA-1-ADRENOCEPTOR SUBTYPES IN HUMAN AND CANINEPROSTATE MEMBRANES

Experiments were designed to characterize the predominant subtype of a lpha-1 adrenoceptors in human and canine prostate tissue. The chemical ]iodo-4-hydroxyphenyl)-ethyl-aminomethyl-tetralone bound in a specifi c, saturable manner to a single class of binding sites in membranes th at expressed recombinant hamster alpha-1B, bovine alpha-1C and rat alp ha-1D receptors expressed in rat-1 fibroblasts and to those from prost ate tissue. Competition assays with human and canine prostate membrane s revealed only a single class of binding sites. Binding affinity in b oth human and canine prostate most significantly correlated with bindi ng affinity for the recombinant bovine alpha-1C receptor (r = .98 huma n, .95 canine). Further analysis with leverage plots demonstrated that binding affinity in human and canine prostate tissue is best predicte d by binding affinity to recombinant bovine alpha-1C (P <.01 human and P <.001 canine). These data are consistent with a single class of alp ha-1 adrenoceptors in human and canine prostate tissue, which is best represented as the alpha-1C subtype.