Origin of spontaneous rhythmicity in smooth muscle
Origin of spontaneous rhythmicity in smooth muscle
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DOI：
10.1113/jphysiol.2005.098376
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发表时间：
2006-01-01
影响因子：
5.5
通讯作者：
Thornbury, K
中科院分区：
文献类型：
--
作者：
McHale, N;Hollywood, M;Thornbury, K
有节奏的电活动是大多数平滑肌肉的特征，但其力学后果可能从规律性的快速相性收缩到持续性收缩。多年来，人们一直认为自发电活动起源于平滑肌细胞，但最近发现，在许多器官中存在着特殊的起搏细胞，这些细胞在形态和功能上与平滑肌不同，并且前者是自发电活动的来源。这样的起搏器功能在胃肠道的ICC中有很好的文献记载，但越来越多的证据表明，ICC样细胞在其他类型的平滑肌中也发挥着类似的作用。我们最近发现，在兔的尿路中存在特殊的起搏细胞，这些细胞在新鲜分离时自发活跃，很容易与强场照下的平滑肌细胞区分开来，并且相对容易使用膜片钳和共聚焦成像技术进行研究。最近的结果表明，兔尿路间质细胞的钙振荡是由兰尼定敏感的细胞内钙释放引起的，振荡频率对外界钙浓度非常敏感，而初级振荡到传播的钙波的转换依赖于IP3诱导的钙释放。
Rhythmic electrical activity is a feature of most smooth muscles but the mechanical consequences can vary from regular rapid phasic contractions to sustained contracture. For many years it was thought that spontaneous electrical activity originated in smooth muscle cells but recently it has become apparent that there are specialized pacemaker cells in many organs that are morphologically and functionally distinct from smooth muscle and that the former cells are the source of spontaneous electrical activity. Such a pacemaker function is well documented for the ICC of the gastrointestinal tract but evidence is accumulating that ICC-like cells play a similar role in other types of smooth muscle. We have recently shown that there are specialized pacemaking cells in the rabbit urethra which are spontaneously active when freshly isolated, readily distinguishable from smooth muscle cells under bright field illumination and relatively easy to study using patch-clamp and confocal imaging techniques. Recent results suggest that calcium oscillations in isolated rabbit urethral interstitial cells are initiated by calcium release from ryanodine sensitive intracellular stores, that oscillation frequency is very sensitive to the external calcium concentration and that conversion of the primary oscillation to a propagated calcium wave depends upon IP3-induced calcium release.