Diener M, Rummel W, Mestres P, Lindemann B
Institut für Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Federal Republic of Germany.
J Membr Biol. 1989 Apr;108(1):21-30. doi: 10.1007/BF01870422.
Chloride channels from rat colonic enterocytes were studied using the patch-clamp technique. After removal of mucus, inside-out patches were excised from the apical membrane of intact epithelium located at the luminal surface. They contained spontaneously switching Cl- channels with a conductance of 35-40 pS. The channels were blocked reversibly by anthracene-9-carboxylic acid (1mM). In excised patches from single enterocytes, isolated by calcium removal, the Cl- channels were studied in more detail. The I-V relation was linear between +/- 80 mV. The selectivity was I- greater than Br- greater than Cl- = NO3- greater than F- = HCO3-. Thirty pS Cl- channels were also found on the basolateral membrane of crypts isolated by brief calcium removal. The I-V curve of these Cl- channels was also linear. The results provide direct evidence for the existence of Cl- channels in the apical membrane of surface cells in colonic mucosa. The properties of these channels are similar to those previously observed when incorporating membrane vesicles into planar lipid bilayers. Both results support the validity of the theoretical models describing intestinal secretion.
采用膜片钳技术研究了大鼠结肠肠上皮细胞的氯离子通道。去除黏液后，从位于管腔表面的完整上皮细胞顶端膜上切下内向外膜片。这些膜片中含有自发转换的氯离子通道，电导为35 - 40 pS。这些通道可被蒽-9-羧酸（1 mM）可逆性阻断。在通过去除钙离子分离出的单个肠上皮细胞的膜片中，对氯离子通道进行了更详细的研究。电流-电压关系在±80 mV之间呈线性。选择性为I⁻＞Br⁻＞Cl⁻ = NO₃⁻＞F⁻ = HCO₃⁻。通过短暂去除钙离子分离出的隐窝基底外侧膜上也发现了30 pS的氯离子通道。这些氯离子通道的电流-电压曲线也是线性的。结果为结肠黏膜表面细胞顶端膜中存在氯离子通道提供了直接证据。这些通道的特性与先前将膜囊泡整合到平面脂质双分子层中时观察到的特性相似。这两个结果都支持了描述肠道分泌的理论模型的有效性。
