title: Adrenoceptor mechanisms in the regulation of contractile activity in the human cervix.
abstract: The effects of adrenoceptor agonists and antagonists on the contractile activity of cervical strips from early pregnant and nonpregnant women were studied. Noradrenaline and the alpha-adrenoceptor agonist, phenylephrine, had a stimulatory effect on smooth muscle activity. This response could be blocked totally by the alpha-adrenoceptor antagonist, phenoxybenzamine. Isoprenaline, known to be a beta-adrenoceptor agonist with some alpha-adrenoceptor activity, had stimulatory and inhibitory effects, whereas the beta 2-adrenoceptor agonist, terbutaline, exhibited a pure inhibitory action. The inhibitory effects of isoprenaline and terbutaline were totally blocked by the beta-adrenoceptor antagonist propranolol. In pregnant patients, the sensitivity to noradrenaline was significantly higher, and the inhibitory action of terbutaline was less pronounced, which indicated the predominance of alpha-receptor activity in the uterine cervix during pregnancy.
mesh_terms: D000293:Adolescent; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D002584:Cervix Uteri / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000502:physiology*; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic