Contraction and Relaxation Responses of Isolated Rabbit Seminal Vesicle to Selective beta Subtypes-adrenoceptor Agonists and Antagonists / 대한비뇨기과학회지

ABSTRACT

PURPOSE: This study was aimed at investigating the role of betaadrenoceptor subtypes in mediating the relaxation and contraction of seminal vesicles in rabbits. MATERIALS AND METHODS: Relaxation or contractile responses of epithelium- removed muscle strips of a rabbit seminal vesicle, which were precontracted with 10-5M norepinephrine, to selective betasubtypes-adrenoceptor agonists were observed in an organ bath. The contractile responses induced by isoproterenol were also observed after application of selective antagonists. RESULTS: Isoproterenol showed a concentration-dependent contractile response, but the contractility was weaker than those with phenylephrine and norepinephrine. The betaselective-agonists(xamoterol for beta, clenbuterol for beta and BRL37344 for beta) alone evoked neither contraction nor relaxation. However, the beta- and beta-agonists inhibited the contraction of the precontracted strips with 10-5M norepinephrine, while the beta-agonist enhanced the contraction. The pretreatment with a beta-antagonist(ICI118551) reduced the tension of the strips developed by 10-4M isoproterenol, but the beta-(atenolol) and beta-(SR59230A) antagonists showed no changes in the response. CONCLUSIONS: beta- and beta-adrenoceptors seem to mediate the relaxation of the seminal vesicle, while the beta-adrenoceptor may have a supplementary role in contraction.