Comparison of adrenoceptor subtype expression in porcine and human bladder and prostate

We have quantified and characterized alpha(1)-, alpha(2)- and beta-adrenoceptor 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, respectively, as the radioligands. In porcine male and female detrusor and bladder neck and male prostate, adrenoceptors were detected in the order of abundance beta > alpha(2) much greater than alpha(1) (not detectable), with no major differences between the sexes or between detrusor and bladder neck. In human detrusor and prostate the order of abundance was beta > alpha(2) much greater than alpha(1) (not detectable) and beta much greater than alpha(1) > alpha(2), respectively. The alpha(2)-adrenoceptors in all tissues were homogeneously of the alpha(2A)-subtype as evidenced by competition binding studies with yohimbine, prazosin, ARC 239 and oxymetazoline. The beta-adrenoceptors represented a mixed population with a dominance of the beta(2)-subtype in all tissues 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 detrusor function with respect to adrenoceptor expression. They may be less suitable for studies of bladder neck or prostate function.