Leake R D, Weitzman R E, Fisher D A
Obstet Gynecol. 1980 Dec;56(6):701-4.
Oxytocin (OT) metabolic clearance rates (MCR) were measured during the constant infusion of 4 mU/min synthetic oxytocin (Pitocin) in 22 healthy adult subjects: 6 men, 6 nonpregnant women, and 10 pregnant women. Pregnant subjects were at term and undergoing OT induction of labor. Mean (+/- SEM) baseline plasma OT concentrations were similar for men, pregnant women, and nonpregnant women. OT MCR was 27 +/- 1.8 ml/kg/min in men; 20.6 +/- 2.8 ml/kf/min in nonpregnant women; and 23.1 +/- 2.6 ml/kg/min in pregnant women. These values were statistically similar. The OT MCR corrected to prepregnancy weight was 25.4 +/- 2.0 ml/kg/min. This value is also statistically similar to the values in men and nonpregnant women. OT degradation was studied in vitro in pooled plasma of men, nonpregnant women, pregnant women, and cord blood. No significant degradation was observed in men, nonpregnant women, or cord plasma. There was an 85% per hour decrease in OT concentration in plasma of pregnant women, confirming earlier reports. These results suggest that the cystine amino peptidase enzyme mediating OT degradation in pregnancy plasma is preferentially secreted by trophoblast cells into maternal plasma and does not seem to cross the placental barrier.
在22名健康成年受试者（6名男性、6名未孕女性和10名孕妇）中持续输注4 mU/分钟的合成催产素（缩宫素）期间，测量了催产素（OT）的代谢清除率（MCR）。孕妇已足月且正在接受催产素引产。男性、孕妇和未孕女性的平均（±标准误）基线血浆催产素浓度相似。男性的OT MCR为27±1.8 ml/kg/分钟；未孕女性为20.6±2.8 ml/kg/分钟；孕妇为23.1±2.6 ml/kg/分钟。这些值在统计学上相似。校正至孕前体重的OT MCR为25.4±2.0 ml/kg/分钟。该值在统计学上也与男性和未孕女性的值相似。对男性、未孕女性和孕妇的混合血浆以及脐血进行了OT体外降解研究。在男性、未孕女性或脐血血浆中未观察到明显降解。孕妇血浆中OT浓度每小时下降85%，证实了早期报告。这些结果表明，介导孕期血浆中OT降解的胱氨酸氨基肽酶优先由滋养层细胞分泌到母体血浆中，似乎不会穿过胎盘屏障。
