Blennerhassett M G, Garfield R E
Department of Pathology, McMaster University Health Sciences Center, Hamilton, Ontario, Canada.
Am J Physiol. 1991 Dec;261(6 Pt 1):C1001-9. doi: 10.1152/ajpcell.1991.261.6.C1001.
Gap junctions (GJ) increase between myometrial cells immediately before labor. To provide evidence of their role in cell-to-cell coupling, we evaluated input resistance (Ro) and intercellular spread of Lucifer yellow (LY) in intact preparations of rat longitudinal myometrium of preterm, term, and antiprogesterone-treated preterm delivering animals. LY injected into cells from either term or preterm delivering rats (many GJ) spread rapidly to neighboring cells by 60 s, but in preparations from nondelivering controls required 4-6 min to become detectable in adjacent cells. Ro of cells in preterm nondelivering preparations was 24.1 +/- 0.8 (SE) M omega, but dropped to 12.0 +/- 0.4 M omega (P less than 0.05) at delivery, similar to preterm delivering tissues at 13.8 +/- 0.6 M omega. The putative GJ uncoupling agent octanol reversibly increased Ro of term- and preterm-delivering tissues fourfold (P less than 0.01) within 60 s, and Ro of preterm-nondelivering tissue was further increased so that Ro values were similar among the three classes. These increased Ro values are interpreted as decreased coupling. Both K+ depolarization and oxytocin (10(-8) to 10(-6) M) increased Ro of delivering tissues (P less than 0.05), suggesting that high levels of contractile agonists may lead to reduced cell-to-cell coupling. Therefore, myometrial coupling can be modulated over seconds via GJ permeability as well as over hours by GJ number.
在分娩前，子宫肌层细胞间的缝隙连接（GJ）会增加。为了证明它们在细胞间偶联中的作用，我们评估了早产、足月以及经抗孕激素处理的早产分娩大鼠的完整纵向子宫肌层标本中，细胞的输入电阻（Ro）和荧光黄（LY）在细胞间的扩散情况。将LY注入足月或早产分娩大鼠的细胞中（缝隙连接较多），60秒内LY就能迅速扩散到相邻细胞，但在未分娩对照组的标本中，需要4 - 6分钟才能在相邻细胞中检测到。未分娩的早产标本中细胞的Ro为24.1±0.8（SE）MΩ，但在分娩时降至12.0±0.4 MΩ（P<0.05），与早产分娩组织的13.8±0.6 MΩ相似。推测的缝隙连接解偶联剂辛醇在60秒内使足月和早产分娩组织的Ro可逆性增加了四倍（P<0.01），未分娩的早产组织的Ro进一步增加，使得三类组织的Ro值相似。这些增加的Ro值被解释为偶联减少。钾离子去极化和催产素（10⁻⁸至10⁻⁶ M）均可增加分娩组织的Ro（P<0.05），这表明高水平的收缩激动剂可能导致细胞间偶联减少。因此，子宫肌层的偶联可在数秒内通过缝隙连接的通透性进行调节，也可在数小时内通过缝隙连接的数量进行调节。
