膀胱二聚体Cajal间质细胞的超微结构及其对ATP的电反应

Ultrastructure and responses to ATP of dimmer interstitial cells of Cajal in bladder

目的:为证明膀胱二聚体Cajal间质细胞(interstitial cells of Cajal,ICC)发挥起搏作用提供超微结构和功能学证据。方法:电子显微镜下鉴定组织和培养的豚鼠膀胱二聚体ICC并观察ICC之间的超微联系;体外分离、培养豚鼠膀胱ICC,运用细胞膜片钳技术观察ATP(100μmol/L)刺激下二聚体ICC和单体ICC的兴奋性差别。结果:二聚体ICC中两个ICC细胞胞体紧密相连,细胞之间的间隙小于20 nm,存在大量缝隙连接,局部细胞膜融合,形成联胞体。在ATP(100μmol/L)的刺激下体外培养的二聚体ICC的内向电流幅度为286.9±26.4 pA,显著大于单体ICC的内向电流幅度163.8±18.6 pA(P<0.01)。结论:二聚体ICC具有形成高兴奋起搏电流的超微结构基础,高兴奋性的二聚体ICC可能才是逼尿肌的起搏细胞。

Objective： To confirm dimmer interstitial cells of Cajal （ICC） in bladder are pacemaker cells with the ultra- structural and functional evidences. Methods： Dimmer ICC of guinea pig bladder were identified and the contacts be- tween two single cells of dimmer ICC were observed by electron microscopy. The difference of excitability, elicited by ATP （100 I^mol/L）, between dimmer ICC and monomer ICC isolated and cultured in vitro, was investigated by using patch clamp technique. Results： Two single cell bodies of dimmer ICC were closely in contact, the gap between the cells is less than 20 nm. There were a large number of gap junctions between two single cells of dimmer ICC. The boundaries were blurred between the local cell membrane. The inward current of dimmer ICC （286.9 ＋ 26.4 pA） , stimulated by ATP （ 100mol/L）, was significantly greater than that of monomer ICC （ 163.8 ＋ 18.6 pA, P 〈 0.01 ）. Conclusion： Dimmer ICC in bladder have the ultrastructural basis of pacemaker current and are likely to be pacemaker cells to excite detrusor.