alpha(1)- and alpha(2)-adrenoceptors in BPH

The dynamic obstruction of the bladder outlet secondary to benign prostatic hyperplasia (BPH), and the contractile properties of the human prostate ar e mediated primarily by alpha(1)-adrenoceptors. There are now at least thre e subtypes (A, B, and D) of alpha(1)-adrenoceptors, and recent work reveale d that alpha(1A)-adrenoceptor and alpha(1B)-adrenoceptor may have a prime r ole for prostatic obstruction, and contraction of artery, respectively. Ver y recently, the presence of a low affinity alpha(1)-adrenoceptor for prazos in, named alpha(1L), in the human BPH tissue has been determined. Because t he DNA sequence of alpha(1L)-adrenoceptor has not yet been cloned, the alph a(1L)-adrenoceptor may be another form of the alpha(1A)-adrenoceptor, or an other pharmacologically distinct alpha(1)-adrenoceptor which mediates the n orepinephrine-induced contraction of the prostatic smooth muscle. Furthermo re, the contribution of alpha(1)-adrenoceptors in the prostate to symptoms (not only obstructive, but irritative symptoms) which are elicited by prost atic obstruction remains to be determined.