Cohen B J, Lechene C
New England Deaconess Hospital, Boston, MA.
Biol Cell. 1989;66(1-2):191-5.
The (Na,K)-pump develops and maintains ionic gradients that are of fundamental importance for proper function of most animal cells. These gradients are utilized in the form of ionic leak pathways by a number of special and general cell processes (e.g., nerve conduction, nutrient transport, pH regulation). As the sodium gradient in particular energizes many vital cell processes, alterations in cell activity will often be manifest as changes in sodium entry. The (Na,K)-pump rate varies accordingly, in order to maintain balance between Na entry and exit thereby maintaining the potential energy of the cell. Acute changes in sodium influx are balanced by increases in activity of existing pump units, with only a small change in intracellular sodium concentration. This is possible because intracellular is normally poised on the steep limb of the concentration versus activity curve for the (Na,K)-pump, at a point well below maximal activity, allowing large increases in (Na,K)-pump rate with only small changes in sodium concentration. If the increase in sodium influx is prolonged, it appears that the cell responds by synthesizing new pumps, allowing intracellular sodium concentration to return to its original values. Though increases in (Na,K)-pump activity must be accompanied by increases in potassium leak rates, in the experiments we have presented, there does not appear to be direct functional coupling between (Na,K)-pump and the K leak pathways. In these situations the matching of active influx and passive efflux of K short-term appears to occur by mechanisms not directly related to (Na,K)-pump activation.
（钠钾）泵形成并维持离子梯度，这对大多数动物细胞的正常功能至关重要。许多特殊和一般的细胞过程（如神经传导、营养物质运输、pH调节）以离子泄漏途径的形式利用这些梯度。特别是由于钠梯度为许多重要的细胞过程提供能量，细胞活动的改变通常会表现为钠内流的变化。（钠钾）泵的速率相应变化，以维持钠进出的平衡，从而维持细胞的势能。钠内流的急性变化通过现有泵单元活性的增加来平衡，细胞内钠浓度仅有微小变化。这是可能的，因为细胞内通常处于（钠钾）泵浓度与活性曲线的陡峭部分，处于远低于最大活性的点，允许（钠钾）泵速率大幅增加而钠浓度仅有微小变化。如果钠内流的增加持续时间较长，细胞似乎会通过合成新的泵来做出反应，使细胞内钠浓度恢复到其原始值。尽管（钠钾）泵活性的增加必然伴随着钾泄漏速率的增加，但在我们所展示的实验中，（钠钾）泵与钾泄漏途径之间似乎不存在直接的功能耦合。在这些情况下，钾的主动内流和被动外流的短期匹配似乎是通过与（钠钾）泵激活不直接相关的机制发生的。
