Mechanical Responses of the Isolated Cervix and Uterine Horn of Pregnant Rats Near Term to Drugs

Abstract

The responses of circularly cut strips of cervix and uterine horn from rats on days 20 and 22 of pregnancy to drugs were compared in vitro. The cervix exhibited similar responses and sensitivities to acetylcholine, bradykinin, prostaglandin (PG) F2a (day 20) and isoprenaline (day 20) as did the uterine horn but was less sensitive or responded less consistently to isoprenaline (day 22), oxytocin and PGEj. PGE2 was more potent on the cervix (day 20). Before term the relatively inextensible connective tissue of the cervix plus contractions of the smooth muscle would help to prevent foetal expulsion. At term the cervical smooth muscle is sufficiently unresponsive to allow cervical dilatation.

Cervical diameter in relation to uterine and cervical EMG activity in early postpartum dairy cows with retained placentas after PGF2alpha induced calving

“…It has been shown before that the cervix displays its own contractility pattern during parturition and that its response to prostaglandin E and oxytocin differs from that of the uterus [22,24,37]. Our study shows that such differences in contractility also exist after parturition and further emphasizes that the cervix has to be regarded as an organ with an own function and acting partly independent of the uterus.…”

Smooth Muscle Pharmacology in the Isolated Virgin and Pregnant Rat Uterus and Cervix

“…Second, the pregnant cervix lost contractile responsiveness to oxytocin, whereas the uterus did not. This finding was consistent with observations made by Hollingsworth and Isherwood (1978). Using term pregnant (day 22) strips of rat cervix, they demonstrated a reduced contraction to a given concentration (1 or 10 mu/ml) of oxytocin; a concentration-response curve was not performed.…”

“…The smooth muscle cells within the deep stromal layer of the cervix are even less well defined, and their function has been described as anything from secretory to contractile (Tiltman, 1998). The few studies that investigate the isolated cervix pharmacologically underscore the paucity of work done in this area (Hollingsworth and Isherwood, 1978;Petersen et al, 1991). Uterus and Cervix: Similarity in Responses.…”

The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

“…The increases observed in untreated pregnant rats in the present results confirm the observations of Harkness & Nightingale (1962) and Rundgren (1974). The cervix of the late pregnant rat contains smooth muscle which is capable of responding to prostaglandins, oxytocin and neurotransmitters, but on Day 22 maximal responses of spirally cut cervical strips were small relative to those of the uterine horn (Hollingsworth & Isherwood, 1978, 1979, perhaps due to the lower proportion of smooth muscle in the cervix (Harkness & Harkness, 1959). It is therefore reasonable to account for changes in the extensibility of the cervix mainly in terms of changes in the connective tissue.…”

“…The cervix was defined as the less vascular tissue with parallel lumina be¬ tween the uterine horns and the vagina (Harkness & Harkness, 1959;Hollingsworth & Isherwood, 1978). Weight of total products of conception (fetuses, placentas, amniotic fluid and membranes), and numbers of alive and dead fetuses per litter were routinely determined.…”