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目的 :研究人类小肠上皮细胞 (Intestine40 7cell lines)膜上钙激活性钾通道的分子生物学特征及其电生理学特性。方法 :用 RT- PCR方法检测培养的人类小肠上皮细胞膜上钙激活性钾通道的表达形式 ,用膜片钳的全细胞记录及单通道记录法探讨了该通道的电生理学特点。结果 :RT- PCR证实该细胞系有 interm ediate- conductance(IK)钙激活性钾通道表达 ,而没有 large- conductance(BK)和 small- conductance(SK)钙激活性钾通道的表达。电生理学研究表明 ,Ionom ycin引导的全细胞电流显示该钙激活性钾电流具有内向整流性并可被特异度 IK钙激活性钾通道阻断剂 clotrimazole所抑制 ,但特异度 SK钙激活性钾通道阻断剂 apam in对该电流无明显抑制作用。单通道记录法证实该通道的电导为 30± 2 p S,通道活性对细胞内 Ca2 +浓度有明显依赖性。结论 :分子生物学和电生理研究证实了人类小肠上皮细胞膜上有 IK钙激活性钾通道 ,其生理学意义有待进一步研究
AIM: To investigate the molecular biology and electrophysiological characteristics of calcium-activated potassium channels in human intestinal epithelial cells (Intestine 40 7 cells). Methods: The expression of calcium-activated potassium channel in cultured human intestinal epithelial cell membrane was detected by RT-PCR. The electrophysiological characteristics of the channel were investigated by patch-clamp whole-cell recording and single-channel recording. Results: RT-PCR confirmed that this cell line has calcium-activated potassium channel expression of interm ediate-conductance (IK) but not calcium-activated potassium channel of large-conductance (BK) and small-conductance (SK). Electrophysiological studies have shown that Ionom ycin-induced whole-cell currents show that this calcium-activated potassium current has inward rectification and can be inhibited by the specific IK calcium-activated potassium channel blocker clotrimazole but that the specific SK calcium-activated potassium channel Blocking agent apamin no significant inhibitory effect on the current. The single-channel recording method confirmed that the conductance of this channel was 30 ± 2 pS, and channel activity was significantly dependent on intracellular Ca2 + concentration. CONCLUSIONS: Molecular biology and electrophysiological studies confirm the presence of IK-Ca2 + channels in human intestinal epithelial cells, and their physiological significance needs further study