Eur J Pharmacol 2006 Apr 28; (Read article online)

Gray KT, Ventura S

The subtype of alpha(1)-adrenoceptor mediating noradrenaline-induced contractile responses in isolated mouse prostate glands was investigated. Adrenoceptor agonists were able to produce concentration-dependent contractions with the following rank order of potency: adrenaline>/=noradrenaline>/=clonidine=phenylephrine>dopamine>/=isoprenaline. Concentration-response curves to noradrenaline of the prostatic smooth muscle were antagonised by prazosin, N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha, alpha-dimethyl-1H-indole-3-ethanamine (RS-17053), 2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane (WB 4101), tamsulosin and yohimbine with mean antagonist affinity estimates (pA(2) or apparent pK(B)) of 8.12+/-0.10, 6.56+/-0.11, 8.38+/-0.06, 10.14+/-0.19 and 7.38+/-1.36 respectively. Propranolol (1 muM) had no antagonist activity (P=0.994, n=6). Yohimbine (0.01, 0.1, 1 muM) had no antagonist activity in the presence of prazosin (0.1 muM) (P>/=0.059). The results obtained indicate that alpha(1)-adrenoceptors mediate the contractile response in isolated preparations of the mouse prostate. Furthermore, the particular subtype of alpha(1)-adrenoceptor mediating the response to exogenously administered noradrenaline corresponds to the alpha(1L)-subtype, the same subtype as that which has been shown to mediate noradrenaline-induced contractile activity in the human prostate.