Rapoport S I
Biophys J. 1971 Aug;11(8):631-47. doi: 10.1016/S0006-3495(71)86243-4.
A model for the Na-K exchange pump was applied to data on Na(+)-loaded frog sartorius muscle, and was used to relate the rate of adenosine triphosphate (ATP) hydrolysis to the electrical properties of the cell membrane. Membrane hyperpolarization was considered to arise from an electrical current which was produced by the hydrolysis reaction coupled to ion movements, and which flowed across the membrane. The reaction rate, as calculated from hyperpolarization, agreed with direct measurements of ATP hydrolysis and with the rate estimated from Na(+) tracer efflux studies. Although Na(+) is actively extruded, the model showed that K(+) is inwardly transported if the potassium permeability of the membrane is less than about 6.6 x 10(-6) cm/sec, as is suggested by resistance data. Calculations indicated that the reaction conductance L(rr) was relatively constant when compared with the reaction rate and reaction free energy for large changes in internal and external ionic concentrations. Its value agreed with the value obtained from the dependence of Na(+) tracer efflux on external K(+). A set of experiments was suggested which would provide a more complete interpretation of the data.
将钠钾交换泵模型应用于钠负载青蛙缝匠肌的数据，并用于将三磷酸腺苷（ATP）水解速率与细胞膜的电特性联系起来。膜超极化被认为是由水解反应与离子运动耦合产生的电流引起的，该电流流过细胞膜。根据超极化计算出的反应速率与ATP水解的直接测量值以及从钠示踪剂外流研究估计的速率一致。尽管钠被主动排出，但该模型表明，如果膜的钾通透性小于约6.6×10^(-6) cm/秒（电阻数据表明如此），钾会向内运输。计算表明，当内部和外部离子浓度发生较大变化时，与反应速率和反应自由能相比，反应电导L(rr)相对恒定。其值与从钠示踪剂外流对外部钾的依赖性获得的值一致。提出了一组实验，这将对数据提供更完整的解释。
