钙调蛋白在介导大鼠结肠平滑肌细胞Ca^2＋内流的作用机制

【目的】探讨钙调蛋白在介导大鼠结肠平滑肌细胞中Ca^2＋内流的作用机制。【方法】将酶解分离好的大鼠结肠平滑肌细胞，随机分为以下4组：①对照组；②EGTA组；③EGTA＋Veraparmil组；④EGTA＋W7组。荧光探针Fura-2／AM标记细胞内游离Ca^2＋，荧光分光光度计检测大鼠结肠平滑肌细胞Ca^2＋浓度。【结果】在无Ca^2＋缓冲液中加入EGTA（1mmol／L）使Ca^2＋浓度由静息时（82．24±3．65）nmol／L升高至（267．45±4．86）nmol／L，继之，向细胞外液中引入两种浓度的Ca^2＋（1．5mmol／L和3．0mmol／L），导致Ca^2＋浓度进一步升高，分别为（470．23±4．21）hmol／L、（945．32±3．56）nmol／L．上述升高效应对L型电压操纵性钙通道阻滞剂维拉帕米（verapamil，5μmol／L）不敏感（P〉0．05），但钙调蛋白抑制剂W7对上述升高效应有抑制作用（P〈0．01）。【结论】钙调蛋白参与大鼠结肠平滑肌细胞的钙内流。钙调蛋白抑制剂W7能抑制由EGTA引起的细胞钙内流。这对于进一步深入研究钙通道活性改变，为预防和控制因胃肠动力紊乱所致的消化管疾病具有重要意义。

Mechanism of Calmodulin Mediating Ca2+ Influx in Colon Smooth Muscle Cells in Rats

[Objective]To explore the mechanism of calmodulin mediating Ca^2＋ influx in colon smooth muscle cell in rats. [Methods] Colon smooth muscle cells in rats were divided into control group, EGTA group, EGTA＋ verapamil group and EGTA ＋ W7 group. Intracellular free Ca^2＋ was labeled by Fura-2/AM fluorescent probe, and [Ca^2＋ ] in colon smooth cells in rats was measured by fluorospectrophotometer. [Results] In the buffer of absence of Ca^2＋ , EGTA（lmrnol/L） could elevate [Ca^2＋] from （82.24±3.65）nmol/L to （267.45±4.86）nmol/L. And then two concentrations of Ca^2＋ was added into the extracellular solution, which resulted Ca^2＋ further elevated to 470.23 ±4.21）nmol/L and （945.32±3.56）nmol/L, respectively. The elevated response was blocked by W7（ P 〈0.01）, but was insensitive to L-type voltage calcium channel blocker veraparnil （ P 〉0. 05）. [Conclusion] Calmodulin involves in Ca^2＋ influx in colon smooth muscle cells. The inhibitor of calmodulin such as W7 can inhibit Ca^2＋ influx caused by EGTA. It is very important to further study the change of calcium channel for preventing and control digestive disease caused by gastrointestinal mobility disorder.