Beta-adrenoceptor agonist activity of labetolol on the isolated uterus of the rat.
Isoprenaline produced dose-dependent reductions of responses of the isolated uterus of the rat produced by an EC(80) of acetylcholine. Propranolol acted as a competitive antagonist to isoprenaline. Labetolol also reduced the acetylcholine-induced contractions but was much less potent than isoprenaline. The greatest reduction was smaller than that produced by isoprenaline. Propranolol antagonized the lower doses of labetolol. It is suggested that labetolol possesses partial agonist activity at the beta-adrenoceptors of the rat isolated uterus.
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000318:Adrenergic beta-Agonists; D000818:Animals; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007741:Labetalol / Q000494:pharmacology*; D051381:Rats; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000294:innervation*
D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D007545:Isoproterenol; D000109:Acetylcholine; D007741:Labetalol