Sanders K M, Koh S D, Ordög T, Ward S M
Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA.
Neurogastroenterol Motil. 2004 Apr;16 Suppl 1:100-5. doi: 10.1111/j.1743-3150.2004.00483.x.
Considerable work has led many to conclude that interstitial cells of Cajal (ICC) are the pacemaker cells of the gastrointestinal (GI) tract. These cells form electrically coupled networks within the pacemaker regions of the GI tract, and ICC are electrically coupled to smooth muscle cells. ICC express unique ion channels that periodically produce inward (pacemaker) currents. Recent work has suggested that the inward current is produced by a calcium (Ca2+)-regulated, nonselective cation conductance. Channels responsible for this conductance oscillate in open probability in response to the periodic drop in intracellular Ca2+ concentration during the slow wave cycle. Pacemaker activity generates slow waves that are propagated actively through ICC networks. Depolarization coordinates the pacemaker activity through the ICC network by activating a dihydropyridine-resistant Ca2+ conductance. Entry of small amounts of Ca2+ into ICC entrains spontaneous pacemaker activity and produces cell-to-cell propagation of slow waves. This review discusses the mechanisms and conductances involved in generation and propagation of electrical slow waves in ICC.
大量研究使许多人得出结论，即 Cajal 间质细胞（ICC）是胃肠道（GI）的起搏细胞。这些细胞在胃肠道的起搏区域内形成电耦合网络，并且 ICC 与平滑肌细胞电耦合。ICC 表达独特的离子通道，这些通道周期性地产生内向（起搏）电流。最近的研究表明，内向电流是由钙（Ca2+）调节的非选择性阳离子电导产生的。负责这种电导的通道在慢波周期内，会响应细胞内 Ca2+ 浓度的周期性下降而在开放概率上发生振荡。起搏活动产生慢波，这些慢波通过 ICC 网络进行主动传播。去极化通过激活对二氢吡啶不敏感的 Ca2+ 电导，来协调通过 ICC 网络的起搏活动。少量 Ca2+ 进入 ICC 会带动自发的起搏活动，并产生慢波的细胞间传播。本综述讨论了 ICC 中电慢波产生和传播所涉及的机制和电导。
