THE INNERVATION OF THE RATCERVIX AND ITS PHARMACOLOGY In vitro AND In vivo

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Abstract
1 Contractions of the rat cervix and uterine horns were measured both in vitro and in vivo as changes in luminal perfusion pressure during perfusion at constant flow. 2 Spontaneous cervical and uterine horn contractions in vitro were reduced from rats pre-treated with 17β-oestradiol compared to those ovariectomized only or those pre-treated with 17β-oestradiol plus progesterone. 3 The rat cervix exhibited similar in vitro sensitivities to methacholine, oxytocin, isoprenaline and phenylephrine as did the uterine horns. 4 Transmural stimulation produced cervical and uterine horn contractions, which were blocked by hyoscine or tetrodotoxin, suggesting a cholinergic motor innervation. This was supported by histological findings. 5 In vivo, the injections of propranolol (1.9 × 10−7 mol/kg) or pempidine (3.2 or 6.4 × 10−6 mol/kg) were followed by large cervical and smaller uterine horn contractions, suggesting an adrenergic inhibitory tone mediated by β-adrenoceptors. 6 The evidence for a cervical sphincter is discussed.