Young R C
Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina, USA.
J Soc Gynecol Investig. 2000 May-Jun;7(3):146-52. doi: 10.1016/s1071-5576(00)00041-1.
This article describes the action potential-calcium wave hypothesis of uterine contractility. Two known mechanisms of intercellular tissue-level signaling are merged into a single hypothesis of organ-level signaling. This hypothesis provides a framework with which to link cellular physiology with organ function. The two mechanisms of tissue-level signaling considered are action potential propagation and intercellular calcium waves. A great body of literature exists regarding the electrical excitability of smooth muscle and myometrium. Despite this knowledge, it does not seem possible to reconcile the familiar uterine contraction profile with known parameters of cellular physiology unless a second mechanism of intercellular communication is postulated. Intercellular calcium waves fit the requirements needed for the second mechanism: slow speed, ability to raise intracellular free calcium, and ability to signal over hundreds of micrometers. The premise of the action potential-calcium wave hypothesis is that action potentials propagate rapidly throughout the uterus, initiating intercellular calcium waves. As the intercellular calcium waves propagate slowly through the bundles, myocytes are recruited to participate in the contraction. This article reviews and summarizes the literature on calcium waves in human myometrium and presents evidence to support the combination of these mechanisms. Extension of the hypothesis suggests that the functional unit of the laboring human uterus is the smooth-muscle bundle, and that the frequency and strength of uterine contractions are separate but linked physiologic characteristics of labor.
本文描述了子宫收缩力的动作电位 - 钙波假说。两种已知的细胞间组织水平信号传导机制被整合为一个器官水平信号传导的单一假说。该假说提供了一个将细胞生理学与器官功能联系起来的框架。所考虑的两种组织水平信号传导机制是动作电位传播和细胞间钙波。关于平滑肌和子宫肌层的电兴奋性存在大量文献。尽管有这些知识，但除非假定细胞间通讯的第二种机制，否则似乎不可能将熟悉的子宫收缩模式与细胞生理学的已知参数相协调。细胞间钙波符合第二种机制所需的条件：速度慢、能够提高细胞内游离钙以及能够在数百微米范围内进行信号传导。动作电位 - 钙波假说的前提是动作电位在整个子宫中快速传播，引发细胞间钙波。当细胞间钙波缓慢通过肌束传播时，肌细胞被募集参与收缩。本文回顾并总结了关于人子宫肌层钙波的文献，并提供了支持这些机制结合的证据。该假说的扩展表明，分娩时人子宫的功能单位是平滑肌束，并且子宫收缩的频率和强度是分娩时相互独立但又相互关联的生理特征。
