氯化氨甲酰胆碱对糖尿病大鼠胃窦平滑肌细胞膜电位的作用

目的通过研究糖尿病胃运动障碍大鼠胃窦平滑肌细胞膜电位变化及其对氯化氨甲酰胆碱(carbachol, CCH)反应,探讨糖尿病大鼠胃电节律失常及胃运动障碍原因.方法健康2个月大小Wistar大鼠50只,分为糖尿病组和正常对照组,用链尿佐菌素建立大鼠糖尿病模型,3个月后记录胃电图,测定胃排空时间,然后用激光共聚焦方法测定胃窦平滑肌细胞膜电位,观察不同浓度的氯化氨甲酰胆碱对膜电位的影响.结果与正常大鼠相比,糖尿病大鼠胃电节律失常明显增加,异常节律指数和慢波频率变异系数分别高达30.6%和23.5%,均显著高于正常组(分别为10%和17.5%),糖尿病大鼠胃排空明显延迟,但其胃窦平滑肌细胞膜电位无明显改变;应用CCH后,糖尿病大鼠胃窦平滑肌细胞对CCH敏感性增加.结论糖尿病胃窦平滑肌细胞对胆碱能神经递质敏感性增加,可能是糖尿病胃电节律失常及胃排空障碍原因之一.

Effect of carbachol on membrane potential of smooth muscle cells of gastric antrum of diabetic rats

Objective To study the effect of carbachol(CCH) on membrane potential of smooth muscle cells of gastric antrum of diabetic rats to verify the mechanism of gastric motility disturbance.Methods Fifty healthy Wistar rats of 2-month old,weighing 100-160 g,were divided into the control group(n=20) and diabetes mellitus group(n=30).Three months after the establishment of the rat model of diabetes by intraperitoneal injection of 60 mg/kg streptozotocin,gastric emptying time and gastric electrical activity were measured,and the resting membrane potentials of smooth muscle cells in antrum were measured by confocal laser scanning microscopy,then treated with carbachol of 10~(-9) mmol/L,10~(-8) mmol/L,10~(-7) mmol/L,the membrane potentials were measured.Results As compared with the normal rats,gastric emptying time in diabetic rats was significantly longer and abnormal gastric electric rhythm was significantly increased,the abnormal rhythm index(ARI) and the coefficient of variation(CV) of slow wave frequency in diabetic rats were significantly higher,but the resting membrane potentials remained unchanged and the sensitivity of CCH-induced membrane depolarization was increased.Conclusion The increase of sensitivity of CCH-induced membrane depolarization may be involved in the diabetes-induced gastric motor disorders.