Miller S M, Garfield R E, Daniel E E
Department of Neurosciences, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
Am J Physiol. 1989 Jan;256(1 Pt 1):C130-41. doi: 10.1152/ajpcell.1989.256.1.C130.
The hypothesis that gap junction (GJ) formation between myometrial cells at term improves electrical coupling was tested. We measured the spread of electrical excitation from six extracellular electrodes aligned on uterine strips in either the longitudinal (axial) or transverse (circumferential) direction. Spontaneous bursts propagated over the entire 15-mm recording distance in the axial direction at both preterm and parturition and showed some characteristics of a system of coupled relaxation oscillators. However, individual spikes within the bursts propagated further and with higher velocity at parturition than at preterm. In the circumferential direction, both bursts and individual spikes propagated further at parturition than before. Propagation in this axis at parturition appeared to require an intact circular muscle layer. Spikes evoked by electrical stimulation also propagated further and with higher velocity in both axes at parturition. Electron microscopy showed many GJs between uterine smooth muscle cells during parturition, but few and sometimes no GJs at preterm. Thus improved propagation was associated with increased GJ contact between myometrial cells, consistent with the hypothesis that gap junction formation at term improves electrical coupling.
我们对足月时子宫肌层细胞间形成缝隙连接（GJ）可改善电偶联这一假说进行了验证。我们从沿子宫条纵向（轴向）或横向（环向）排列的六个细胞外电极测量电兴奋的传播。早产和分娩时，自发脉冲均沿轴向在整个15毫米记录距离上传播，并表现出耦合弛豫振荡器系统的一些特征。然而，分娩时脉冲内的单个尖峰比早产时传播得更远且速度更快。在环向，分娩时脉冲和单个尖峰都比之前传播得更远。分娩时在该轴向上的传播似乎需要完整的环形肌层。电刺激诱发的尖峰在分娩时在两个轴向上也传播得更远且速度更快。电子显微镜显示，分娩期间子宫平滑肌细胞之间有许多缝隙连接，但早产时很少，有时甚至没有缝隙连接。因此，传播改善与子宫肌层细胞间缝隙连接接触增加有关，这与足月时形成缝隙连接可改善电偶联的假说一致。
