Contractile responses to α1-adrenoceptor agonists in isolated human male and female urethra

摘要: Objective To investigate the contractile responses mediated through α1-adrenoceptors in human urethra and to evaluate effectiveness of NS-49 [(R)-(–)-3′-(2-amino-1-hydroxyethyl)-4′-fluoromethanesulphonanilide hydrochloride], a novel α1-adrenoceptor agonist, against contraction urethra. Materials methods The were assessed 10 male prostatic urethrae six female urethrae. Antagonism was evaluated using phenylephrine, nonselective cumulatively applied > 20 min after applying 0.1 μmol/L prazosin or 5-methylurapidil, selective α1A-adrenoceptor antagonist. Agonism determined both obtain concentration-response curve for agonist. Results Phenylephrine caused contract, showed high potency efficacy. Prazosin antagonized these contractions with low affinity (apparent pKB 8.30 urethrae). 5-Methylurapidil, also 7.88 Noradrenaline phenylephrine A α1A-and α1L-adrenoceptor NS-49, induced moderate efficacy, whereas methoxamine Norephedrine very weak agonist. Conclusion In urethra, phenylephrine-induced α1L-adrenoceptors not α1A-adrenoceptors. Contractions by mainly α1L-adrenoceptors, may therefore be useful treatment urinary stress incontinence, minimal side-effects because it has subtype selectivity.