Schultz S G
Department of Integrative Biology, University of Texas Medical School, Houston 77225, USA.
J Exp Zool. 1997 Dec 1;279(5):476-83. doi: 10.1002/(sici)1097-010x(19971201)279:5<476::aid-jez10>3.0.co;2-6.
In all Na(+)-absorbing and Cl(-)-secreting epithelia, an increase in the activity of the Na+,K(+)-pump at the basolateral membrane is accompanied by an increase in the K+ conductance of that barrier and vice versa. We have recently identified an ATP-regulated K+ channel, K(ATP), in basolateral membrane vesicles isolated from Necturus maculosa small intestinal epithelial cells that could be responsible for this parallelism between pump activity and leak. Thus, an increase in pump activity would result in a decrease in local ATP activity and an increase in local ADP activity and, in turn, an increase in the open-probability of the channel whereas a decrease in in pump activity would have the opposite effect. Further, the likelihood that the number of pumps far exceeds the number of leaks per unit area of membrane suggests that the ATP and ADP activities that influence K(ATP) channel activity may differ markedly from the "bulk" cytoplasmic values.
在所有吸收Na⁺和分泌Cl⁻的上皮细胞中，基底外侧膜上Na⁺,K⁺-泵活性的增加伴随着该屏障K⁺电导的增加，反之亦然。我们最近在从黄斑钝口螈小肠上皮细胞分离的基底外侧膜囊泡中鉴定出一种ATP调节的K⁺通道，即K(ATP)，它可能是泵活性与渗漏之间这种平行关系的原因。因此，泵活性的增加将导致局部ATP活性降低和局部ADP活性增加，进而导致通道开放概率增加，而泵活性降低则会产生相反的效果。此外，泵的数量远远超过单位膜面积渗漏数量的可能性表明，影响K(ATP)通道活性的ATP和ADP活性可能与“总体”细胞质值明显不同。
