Harding R, Poore E R, Bailey A, Thorburn G D, Jansen C A, Nathanielsz P W
Am J Obstet Gynecol. 1982 Feb 15;142(4):448-57. doi: 10.1016/s0002-9378(16)32389-4.
Myometrial electromyograms were studied in nonpregnant ewes, pregnant ewes throughout the second half of gestation, and during labor and delivery in normal spontaneous vaginal delivery and premature delivery induced by the continuous infusion of synthetic adrenocorticotropin 1-24, 1 microgram x h-1, to the fetus at 120 and 130 days' gestation. The bursts of electromyographic (EMG) activity during estrus were very similar to those seen in the pregnant ewe in the second half of gestation. In the second half of gestation, the bursts of EMG activity lasted a mean of 6.7 minutes and occurred at intervals of 54.7 minutes in utero, without an incision for fetal instrumentation, and were 7.2 minutes in duration, occurring every 46.6 minutes when the uterus had been incised. EMG activity occurred simultaneously at most recording sites within the uterus. There was no evidence to support the view that a uterine pacemaker exists with a fixed location. As delivery approached, the mean duration of each EMG burst began decreasing more than 24 hours before delivery, and the frequency of the bursts increased, demonstrating that the recording of uterine electromyograms provides a precise and sensitive method for the study of the early changes that lead to labor and delivery.
对未孕母羊、妊娠后半期的孕羊以及在妊娠120天和130天时通过向胎儿持续输注1微克/小时的合成促肾上腺皮质激素1 - 24诱导正常自然阴道分娩和早产过程中的分娩期母羊的子宫肌层肌电图进行了研究。发情期的肌电图（EMG）活动爆发与妊娠后半期孕羊的情况非常相似。在妊娠后半期，子宫内未做胎儿监测切口时，EMG活动爆发平均持续6.7分钟，间隔54.7分钟出现一次；子宫切开后，EMG活动爆发持续7.2分钟，每46.6分钟出现一次。子宫内大多数记录部位的EMG活动同时发生。没有证据支持子宫起搏器存在固定位置的观点。随着分娩临近，每次EMG爆发的平均持续时间在分娩前24小时以上开始缩短，爆发频率增加，这表明子宫肌电图记录为研究导致分娩的早期变化提供了一种精确且敏感的方法。
