Kimmich G A, Randles J
Biochim Biophys Acta. 1980 Mar 13;596(3):439-44. doi: 10.1016/0005-2736(80)90131-5.
Membrane potentials maintained by normally-energized intestinal epithelium interfere with an accurate determination of the Na+:sugar coupling stoichiometry associated with Na+-dependent transport systems. The interference is due to the fact that basal Na+ influx is itself a potential-dependent event, and sugar transport induces a membrane depolarization which therefore modifies basal Na+ entry. New information obtained under circumstances in which the membrane potential is maintained near 0 indicates that the true coupling stoichiometry is 2:1 rather than the commonly-accepted value of 1:1. A 2:1 stoichiometry means that cellular electrochemical Na+ gradients are adequate to account for recently observed 70-fold sugar gradients maintained by these cells under certain conditions.
正常供能的肠上皮维持的膜电位会干扰与钠依赖性转运系统相关的钠糖偶联化学计量比的准确测定。这种干扰是由于基础钠内流本身就是一个电位依赖性事件，而且糖转运诱导膜去极化，从而改变基础钠的进入。在膜电位维持在接近0的情况下获得的新信息表明，真正的偶联化学计量比是2:1，而不是普遍接受的1:1。2:1的化学计量比意味着细胞电化学钠梯度足以解释最近观察到的这些细胞在某些条件下维持的70倍的糖梯度。
