Mediation of contraction and relaxation by alpha- and beta-adrenoceptors in the ureterovesical junction of the sheep.
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(-7) M) and yohimbine (10(-7) M), the effect of prazosin being more potent than that of yohimbine. The effect of phenylephrine on alpha 1-adrenoceptors was more potent than that of B-HT 920 on alpha 2-adrenoceptors. Isoproterenol caused a concentration-dependent relaxation that was inhibited by propranolol (10(-6) M), pafenolol (10(-5) M) and butoxamine (10(-5) M). These results suggest that ureterovesical junction contraction is mediated by both alpha 1 and alpha 2-adrenoceptors, alpha 1 predominating over alpha 2. Relaxation is mediated by beta-adrenoceptors of the beta 1 and beta 2 subtypes.
Departamento de Fisiología, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
L
L
Rivera
M
M
Hernández
S
S
Benedito
D
D
Prieto
A
A
García-Sacristán
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002078:Butoxamine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011224:Prazosin / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D012756:Sheep / Q000502:physiology*; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D011412:Propanolamines; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D002078:Butoxamine; D015016:Yohimbine; C036625:pafenolol; D011433:Propranolol; D007545:Isoproterenol; D011224:Prazosin