Mediation of contraction and relaxation by alpha- and beta-adrenoceptors in the ureterovesical junction of the sheep
Rivera, L.; Hernández, M.; Benedito, S.; Prieto, D.; García-Sacristán, A.
Research in veterinary science 52(1): 57-61
1992
ISSN/ISBN: 0034-5288 PMID: 1348146 Document Number: 404020
The effects of alpha- and beta-adrenoceptor agonists and antagonists were studied in the sheep ureterovesical junction. Non-specific adrenergic agonists such as adrenaline and noradrenaline induced contraction in the sheep ureterovesical junction, suggesting a predominance of alpha- over beta-adrenoceptors in this functional unity. An inhibition of the noradrenaline-induced contraction was observed after prior blocking with prazosin (10-7M) and yohimbine (10-7M), the effect of prazosin being more potent than that of yohimbine. The effect of phenylephrine on alpha1-adrenoceptors was more potent than that Of B-HT 920 on alpha2-adrenoceptors. Isoproterenol caused a concentration-dependent relaxation that was inhibited by propranolol (10-6M), pafenolol (10-5M) and butoxamine (10-5M). These results suggest that ureterovesical junction contraction is mediated by both alpha 1 and alpha 2-adrenoceptors, alpha1 predominating over alpha 2. Relaxation is mediated by beta-adrenoceptors of the beta 1 and beta 2 subtypes.