Suzuki H
Department of Physiology, Nagoya City University Medical School, Nagoya, 467-8601, Japan.
Jpn J Physiol. 2000 Jun;50(3):289-301. doi: 10.2170/jjphysiol.50.289.
In many regions of the intestine, a thin layer of interstitial cells of Cajal (ICC) lie in the myenteric region, between the circular and longitudinal muscle layers. ICC are connected by gap junctions to surrounding ICC and also with circular and longitudinal smooth muscle cells, forming a large electrical syncytium. Damage of the ICC causes a disorder in the patterns of rhythmic activity. Isolated ICC produce a rhythmic oscillation of the membrane potential. All these observations have led to the suggestion that ICC may be the pacemaker cell responsible for intestinal activity. Gastric smooth muscles generate slow oscillatory membrane potential changes (slow waves) and spike potentials. The activity is considered to be linked to the metabolism in the cell. Three types of cells located in the gastric wall (circular and longitudinal smooth muscle cells and ICC) produce synchronized electrical responses with different shapes. The electrical responses appear to originate in ICC and then spread to the smooth muscle layers, indicating that ICC may also be the pacemaker cells responsible for gastric activity. However, isolated circular smooth muscle tissues spontaneously generate regenerative potentials, suggesting that there are at least two sites for the initiation of spontaneous activity in the stomach. Regenerative potentials persist in the presence of Ca-antagonists and are inhibited by agents which disrupt intracellular Ca(2+) homeostasis. Depolarization of the membrane elicits regenerative potentials after a long delay and the potentials have long refractory periods. This suggests that an unidentified 2nd messenger may be formed during the delay between membrane depolarization and the initiation of a regenerative potential. In gastric muscles of mutant mice which do not express inositol trisphosphate (InsP(3)) receptors, spike potentials but not slow waves are generated, suggesting the possible involvement of InsP(3) in the initiation of spontaneous activity.
在肠道的许多区域，一层薄薄的 Cajal 间质细胞（ICC）位于肌间区域，即环形肌层和纵形肌层之间。ICC 通过缝隙连接与周围的 ICC 相连，也与环形和纵形平滑肌细胞相连，形成一个大的电突触。ICC 的损伤会导致节律性活动模式紊乱。分离的 ICC 会产生膜电位的节律性振荡。所有这些观察结果都表明，ICC 可能是负责肠道活动的起搏细胞。胃平滑肌产生缓慢的振荡膜电位变化（慢波）和动作电位。这种活动被认为与细胞内的代谢有关。位于胃壁的三种类型的细胞（环形和纵形平滑肌细胞以及 ICC）产生具有不同形状的同步电反应。电反应似乎起源于 ICC，然后传播到平滑肌层，这表明 ICC 也可能是负责胃活动的起搏细胞。然而，分离的环形平滑肌组织会自发产生再生电位，这表明胃中至少有两个自发活动起始位点。再生电位在钙拮抗剂存在的情况下持续存在，并被破坏细胞内 Ca(2+) 稳态的药物所抑制。膜去极化在长时间延迟后引发再生电位，并且这些电位具有长不应期。这表明在膜去极化和再生电位起始之间的延迟期间可能形成了一种未确定的第二信使。在不表达肌醇三磷酸（InsP(3)）受体的突变小鼠的胃肌中，会产生动作电位但不会产生慢波，这表明 InsP(3) 可能参与自发活动的起始。
