COMPARISON OF ADRENOCEPTOR SUBTYPE EXPRESSION IN PORCINE AND HUMAN BLADDER AND PROSTATE

We have quantified and characterized alpha(1)-, alpha(2)- and beta-adr enoceptor subtypes in porcine bladder detrusor and bladder neck, human bladder detrusor, and porcine and human prostate. alpha(1)-, alpha(2) - and beta-adrenoceptor were identified in radioligand binding studies using [H-3]prazosin, [H-3]RX 821002 and [I-125]io docyanopindolol, re spectively, as the radioligands. In porcine male and female detrusor a nd bladder neck and male prostate, adrenoceptors were detected in the order of abundance beta > alpha(2) much greater than alpha(1) (not det ectable), with no major differences between the sexes or between detru sor and bladder neck. In human detrusor and prostate the order of abun dance was beta > alpha(2) much greater than alpha(1) (not detectable) and beta much greater than alpha(1) > alpha(2), respectively. The alph a(2)-adrenoceptors in all tissues were homogeneously of the alpha(2A)- subtype as evidenced by competition binding studies with yohimbine, pr azosin, ARC 239 and oxymetazoline. The beta-adrenoceptors represented a mixed population with a dominance of the beta(2)-subtype in all tiss ues as demonstrated by competition binding with ICI 118,551 and CGP 20 ,712A. We conclude that pigs may be a suitable model for studies of de trusor function with respect to adrenoceptor expression. They may be l ess suitable for studies of bladder neck or prostate function.