alpha(1L)-adrenoceptors mediate noradrenaline-induced contractions of the guinea-pig prostate stroma.
The alpha(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 pD(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-alpha, alpha-dimethyl-1H-indole-3-ethanamine hydrochloride (RS-17053) and (R)-5-[2-[[2-(2-ethoxyphenoxy)ethyl]amino]-2-methylethyl]-2- methoxybenzensulfonamide methanesulphonate hydrate (tamsulosin). Mean pA(2) or apparent pK(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 alpha(1L)-adrenoceptor mediates noradrenaline-induced prostatic smooth muscle contraction in the guinea-pig prostate gland.
Pennefather
J N
JN
Department of Pharmacology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia.
Lau
W A
WA
Chin
C
C
Story
M E
ME
Ventura
S
S
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011467:Prostate / Q000187:drug effects* / Q000502:physiology; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D000077409:Tamsulosin
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D007211:Indoles; C099495:RS 17053; D018340:Receptors, Adrenergic, alpha-1; D013449:Sulfonamides; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D000077409:Tamsulosin; D009638:Norepinephrine; D011224:Prazosin