α 1L-Adrenoceptors mediate noradrenaline-induced contractions of the guinea-pig prostate stroma

• Published in: European journal of pharmacology Vol. 384; no. 1; pp. 25 - 30
• Main Authors: Pennefather, Jocelyn N, Lau, Winnie A.K, Chin, Christina, Story, Margot E, Ventura, Sabatino
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1999
• Subjects: Guinea-pig; Prostate stroma; α 1L-Adrenoceptor; Prostate stroma; Guinea-pig; α 1L-Adrenoceptor
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/S0014-2999(99)00667-6

The α 1-adrenoceptor subtype mediating noradrenaline-induced contractions of the guinea-pig isolated prostatic smooth muscle was investigated. Noradrenaline produced concentration-dependent contractions of the tissue with a mean p D 2 value of 5.26±0.03 ( n=20). These contractions were antagonised by prazosin, 2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride (WB-4101), N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-α, α-dimethyl-1 H-indole-3-ethanamine hydrochloride (RS-17053) and ( R)-5-[2-[[2-(2-ethoxyphenoxy)ethyl]amino]-2-methylethyl]-2-methoxybenzensulfonamide methanesulphonate hydrate (tamsulosin). Mean p A 2 or apparent p K B estimates for the antagonism of noradrenaline were 8.15±0.05 for prazosin; 8.83±0.11 for WB-4101, 7.18±0.14 for RS-17053 and 10.11±0.12 for tamsulosin. The relatively low estimates of the apparent dissociation constant for all antagonists except tamsulosin indicate that an α 1L-adrenoceptor mediates noradrenaline-induced prostatic smooth muscle contraction in the guinea-pig prostate gland.