Hobel C J, Parvez H, Parvez S, Lirette M, Papiernik E
Am J Obstet Gynecol. 1981 Dec 15;141(8):1009-18. doi: 10.1016/s0002-9378(16)32692-8.
The enzyme phenylethanolamine-N-methyl transferase (PNMT) converts norepinephrine (NE) to epinephrine (E), and cathechol-O-methyl transferase (COMT) and monoamine oxidase (MAO) both metabolize NE and E. We were able to measure the activity of these enzymes in myometrial and endometrial samples obtained from 27 pregnant women between 32 and 40 weeks' gestation at the time of cesarean section. In addition, these enzymes were measured in red blood cells and plasma obtained from 45 normal pregnancies between 10 and 40 weeks' gestation. PNMT activity was significantly higher in myometrium than in endometrium. During labor myometrial and red blood cell PNMT activity is significantly lower than in specimens from patients at term not in labor, while myometrial PNMT activity is significantly elevated in patients with dystocia. Under these conditions no significant alterations in myometrial, red blood cell, or plasma COMT or myometrial MAO activities were observed. This study identifies for the first time the presence of PNMT in myometrium, endometrium, and red blood cells and provides the necessary step for the conversion of NE to E, a concept previously limited to the adrenal bland, brain, and heart. This could provide an important physiologic mechanism for the control of uterine activity during pregnancy and parturition.
苯乙醇胺 - N - 甲基转移酶（PNMT）可将去甲肾上腺素（NE）转化为肾上腺素（E），儿茶酚 - O - 甲基转移酶（COMT）和单胺氧化酶（MAO）均可代谢NE和E。我们能够在剖宫产时从27名妊娠32至40周的孕妇获取的子宫肌层和子宫内膜样本中测量这些酶的活性。此外，还对45名妊娠10至40周的正常孕妇的红细胞和血浆中的这些酶进行了测量。子宫肌层中的PNMT活性显著高于子宫内膜。分娩期间，子宫肌层和红细胞中的PNMT活性显著低于未分娩足月患者的样本，而难产患者的子宫肌层PNMT活性显著升高。在这些情况下，未观察到子宫肌层、红细胞或血浆中的COMT或子宫肌层MAO活性有显著变化。本研究首次确定了子宫肌层、子宫内膜和红细胞中存在PNMT，并为NE转化为E提供了必要步骤，这一概念此前仅限于肾上腺、脑和心脏。这可能为孕期和分娩期间控制子宫活动提供重要的生理机制。
