Lammers W J
Department of Physiology, Faculty of Medicine and Health Sciences, PO Box 17666, Al Ain, United Arab Emirates.
Pflugers Arch. 1997 Jan;433(3):287-93. doi: 10.1007/s004240050279.
The propagation of individual action potentials during spontaneous bursts of activity in isolated pregnant rat myometrium in the final stage of pregnancy was analyzed. Simultaneous recordings from 240 extracellular recording sites (inter-electrode distance 1 mm) made it possible to reconstruct, in spatial and temporal details, the conduction of the electrical impulse. On several occasions, the impulse was seen to be conducted in a circular fashion whereby the impulse repeatedly re-excited the myometrium. No evidence was found of circuits rotating around an area of depressed excitability or anatomical obstacle, suggesting that these circuits are similar to those proposed to occur in cardiac muscle by the "leading circuit" model. Because of the anisotropic conduction properties of the myometrium, several circuits revolved in an ellipse with the long axis parallel to the longitudinal fiber direction, similar to functional re-entry in the anisotropic ventricle. Of a total of 46 bursts analyzed, myometrial re-entry occurred in 10 of the bursts. Furthermore, re-entries were found at day 17, day 19 and day 21 ( = term) stages of pregnancy suggesting that re-entry may occur throughout the final stage of gestation. In conclusion, functional re-entry, previously shown in the myocardium, may also occur in the pregnant myometrium. The presence of re-entry in the uterus could underlie the mechanism for uterine tachysystole, leading to dysfunctional labor.
对妊娠末期离体妊娠大鼠子宫肌层自发性活动爆发期间单个动作电位的传播进行了分析。来自240个细胞外记录位点（电极间距1毫米）的同步记录使得能够在空间和时间细节上重建电冲动的传导。有几次，观察到冲动以循环方式传导，由此冲动反复重新兴奋子宫肌层。未发现围绕兴奋性降低区域或解剖学障碍旋转的回路的证据，这表明这些回路与“主导回路”模型提出的在心肌中发生的回路相似。由于子宫肌层的各向异性传导特性，几个回路以长轴平行于纵向纤维方向的椭圆形式旋转，类似于各向异性心室中的功能性折返。在总共分析的46次爆发中，有10次爆发发生了子宫肌层折返。此外，在妊娠第17天、第19天和第21天（足月）阶段发现了折返，这表明折返可能在整个妊娠末期发生。总之，先前在心肌中显示的功能性折返也可能发生在妊娠子宫肌层中。子宫中折返的存在可能是子宫快速收缩机制的基础，导致分娩功能障碍。
