['To observe the expression of beta-3-adrenoceptor in the detrusor muscle in female rats and investigate the relaxant effect of beta-adrenoceptor agonists on detrusor muscle in ovariectomized rats with or without estrogen replacement therapy.', 'We first performed reverse transcriptase-polymerase chain reaction to demonstrate mRNA encoding the beta-3-adrenoceptor in the detrusor muscle from female rats. We then performed pharmacologic and physiologic studies to determine the effect of estrogen replacement therapy on the beta-adrenoceptor-mediated relaxation of the detrusor muscle of the ovariectomized rats.', 'Beta-3-adrenoceptor was expressed in the detrusor muscle in female rats with or without ovariectomy. A nonselective beta-adrenoceptor agonist relaxed precontracted detrusor muscle irrespective of ovariectomy or estrogen replacement in a dose-dependent manner; and a selective beta-3-adrenoceptor agonist relaxed the detrusor muscle more in ovariectomized rats than in ovariectomized rats with estrogen replacement or in control rats.'] Do estrogen levels influence beta-3-adrenoceptor-mediated relaxation of the female rat detrusor muscle?