胆囊收缩素对豚鼠结肠平滑肌及其细胞膜L-型钙电流和膜电位的影响  

Effects of cholecystokinin octapeptide on the contractile activity of guinea-pig colonic smooth muscles,L-type calcium currents and membrane potentials of myocytes

作　　者：祝捷[1] 罗和生[1] 陈玲[1] 梁成柏[1] 夏虹[1] 

机构地区：[1]武汉大学人民医院消化内科,430060

出　　处：《中华医学杂志》2011年第12期840-844,共5页National Medical Journal of China

基　　金：国家自然科学基金面上项目（30871148）

摘　　要：目的 探讨胆囊收缩素8肽（CCK-8S）对豚鼠近端结肠平滑肌及细胞膜L-型钙电流和膜电位的电生理作用及其机制.方法 （1）采用RM6240多道生理信号采集处理系统记录CCK-8S对豚鼠近端结肠平滑肌肌条收缩的影响;（2）检测Fluo-2/AM标记的近端结肠平滑肌细胞膜内钙离子浓度（[Ca2＋]i）变化;（3）用EPC-10膜片钳放大器测量全细胞模式下CCK-8S对近端结肠平滑肌细胞膜静息电位（RP）、动作电位（AP）和L-型钙通道电流（ICa-L）的影响.结果 CCK-8S（10-1mol/L）作用后：（1）豚鼠近端结肠平滑肌肌条收缩幅值和频率分别为对照组的（149±12）%和（132±13）%（均P＜0.05）;（2）近端结肠平滑肌细胞膜的[Ca2＋]i为对照组的（738±24）%（P＜0.05）;（3）RP、AP峰值及AP快速复极时间分别为对照组的（52±9）%、（140±4）%和（61±13）%（均P＜0.05）,该效应可被预先加入的CCK1受体拮抗剂地伐西匹和（或）L-型钙通道阻断剂尼非地平阻断（n=8,均P＜0.05）,而预先向灌流液中加入CCK2受体拮抗剂CI 988后,CCK-8S对RP、AP峰值及AP快速复极时间的作用仍存在;（4）从-60 mV去极化至＋10 mV,ICa-L为对照组的（138±7）%（P＜0.05）,但分别可被相应拮抗剂抑制;当向电极内液加入肝素（10-6 mol/L）或向细胞外液加入staurosporine（10-6 mol/L）后,CCK-8S对Ica-L均没有影响（2.9%±2.6%和1.9%±2.3%,均P＞0.05）.结论 CCK-8S通过CCK1受体促进近端结肠平滑肌自发性收缩频率和强度;其机制与激活1,4,5-三磷酸肌醇介导的蛋白激酶C途径进而促进L-型钙通道开放有关.Objective To investigate the effects and mechanism of cholecystokinin octapeptide （CCK-8S） on the contractile activity of smooth muscles,L-type calcium current and membrane potentials of proximal colon myocytes in guinea pig.Methods （ 1 ） Strips of proximal colon were obtained from adult guinea pigs.The contraction of these stripes was measured by a RM6240 multi-channel physiological signal system.（2） Suspension of single smooth muscle cells （SMCs） were obtained from proximal colon and isolated by enzymatic digestion.The effect of CCK-8S on intracellular calcium concentration （ [Ca2＋] i） of SMCs was examined by fura-2-1oaded miscrofluorimetric measurement.（3） Resting potential （ RP）,action potential （AP） and L-type calcium current （ICa-L ） were recorded by patch-clamp technique.Results （ 1 ）The contractile amplitude and frequency of muscle stripes enhanced by CCK-8S （ 10 -7 mol/L） were （ 149 ±12）% and （132 ± 13 ）% respectively of those of control group （all P 〈 0.05 ）.They were significantly attenuated by pretreating strips with CCK1 receptor antagonist devazepide （ 10-7 mol/L）,L-type calcium channel blocker nifedipine （ 10 -5 mol/L）,Ca2＋ -ATPase inhibitor TG （thapsigargin） （ 10-5 mol/L） and BA （boric acid） （10-5 mol/L） respectively.（2） [Ca2＋]i of SMCs intensified by CCK-8S was （738 ±24）% of that of control group.And it was inhibited by pretreating SMCs with devazepide（all P 〈0.05）.（3） After the superfusion of CCK-8S,RP depolarized to （52 ±9）%,the exogenously stimulated peak values of AP rose to （140±4）% and fast repolarization time of AP decreased to （61 ± 13）% （all P 〈0.05）.They were significantly inhibited when these cells were pretreated with devazepide and/or nifedipine （n = 8,P 〈0.05 for each group） whereas CI 988 had little effect.（4） The CCK-8S-evoked ICa-L of SMCs at the voltage of ＋ 10 mV was boosted to （ 138 ± 7 ）%.Such an effect was suppressed by a pretreat

关 键 词：胆囊收缩素 肌细胞 平滑肌 膜电位 钙通道 L型 受体 

分 类 号：R363[医药卫生—病理学]