Department of Anesthesia and Pain Management, University of Toronto, Toronto, Ontario, Canada.
Anesthesiology. 2013 Sep;119(3):552-61. doi: 10.1097/ALN.0b013e318297d347.
Oxytocin receptor desensitization has been shown to occur in humans at biomolecular level and in isolated rat myometrium; however, its effect on human myometrial contractility has not been demonstrated. The objective of this in vitro study was to investigate the contractile response of human pregnant myometrium to oxytocin after pretreatment with different concentrations of oxytocin for variable durations.
Myometrial samples were obtained from 62 women undergoing elective cesarean deliveries under regional anesthesia. The strips were pretreated with oxytocin 10, 10, 10 M, or physiological salt solution (control) for 2, 4, 6, or 12 h, followed by a dose-response testing with oxytocin 10 to 10 M. Amplitude and frequency of contractions, motility index, and area under the curve during the dose-response period were recorded, analyzed with linear regression models, and compared among groups.
Pretreatment with oxytocin 10 and 10 M significantly reduced motility index (estimate [standard error]: -0.771 [0.270] square root units, P = 0.005 and -0.697 [0.293], P = 0.02, respectively) and area under the curve (-3.947 [1.909], P = 0.04 and -4.241 [2.189], P = 0.05, respectively) compared with control group, whereas pretreatment with oxytocin 10 M did not significantly attenuate contractions. Increase in duration of oxytocin pretreatment from 2 to 12 h significantly decreased amplitude (type 3 generalized estimating equation analysis: chi-square = 14.0; df = 3; P = 0.003), motility index (chi-square = 9.3; df = 3; P = 0.03), and area under the curve (chi-square = 10.5; df = 3; P = 0.02), but not the frequency of oxytocin-induced contractions.
Pretreatment with oxytocin decreases oxytocin-induced myometrial contractions in a concentration and time-dependent manner, likely as a function of the oxytocin receptor desensitization phenomenon.
在生物分子水平和分离的大鼠子宫肌中已证实催产素受体脱敏的发生；然而，其对人子宫肌收缩性的影响尚未得到证实。本体外研究的目的是在不同浓度的催产素预处理不同时间后，研究人妊娠子宫对催产素的收缩反应。
在区域麻醉下，对 62 名接受选择性剖宫产的妇女进行子宫肌取样。将肌条用催产素 10-10-10 M 或生理盐水（对照）预处理 2、4、6 或 12 小时，然后用 10-10 M 催产素进行剂量反应测试。记录剂量反应期间的收缩幅度和频率、运动指数和曲线下面积，用线性回归模型进行分析，并在组间进行比较。
用催产素 10-10 M 预处理可显著降低运动指数（估计[标准误差]：-0.771 [0.270] 平方根单位，P = 0.005 和-0.697 [0.293]，P = 0.02）和曲线下面积（-3.947 [1.909]，P = 0.04 和-4.241 [2.189]，P = 0.05）与对照组相比，而用催产素 10 M 预处理并未显著减弱收缩。催产素预处理时间从 2 小时增加到 12 小时，显著降低了幅度（3 型广义估计方程分析：卡方 = 14.0；df = 3；P = 0.003）、运动指数（卡方 = 9.3；df = 3；P = 0.03）和曲线下面积（卡方 = 10.5；df = 3；P = 0.02），但不影响催产素诱导收缩的频率。
催产素预处理以浓度和时间依赖的方式降低催产素诱导的子宫肌收缩，可能是催产素受体脱敏现象的作用。
