分离的蟾蜍卵母细胞中钠通量的分配

The rate constant for Na efflux from the oocyte calculated from (d/dt) (ln Na(*)]) is only approximately 52% of that calculated from (d/dt)[(ln(dNa(*))dt)]. The difference may be interpreted by supposing that 48% of the internal Na of the oocyte is either bound to proteins or sequestered in cell organelles.2. The mean rate constant for Na efflux was 6.4 x 10(-3) min(-1) corresponding to an apparent Na efflux rate of 13.3 p-mole/cm(2).sec. When this is corrected for the increase in surface area produced by microvilli the true efflux rate is 1.1-1.3 p-mole/cm(2).sec.3. The action of ouabain (1-5 muM) appears to involve two different effects: (a) there is 48-65% inhibition of the membrane Na pump, and (b) there is a release of some of the sequestered Na in the cell.4. Removal of external K causes a 40% reduction in Na efflux although this value may be an underestimation owing to the presence of K which has leaked from the cell and may be retained near the cell surface.5. Raising the external K concentration to 15 mM reduces the inhibitory effect of ouabain by approximately a half.6. It was concluded that the Na pump in the toad oocyte may have a slightly lower level of activity than that in frog muscle, but that its general properties are similar to those in frog muscle and some other animal cells.

根据(d/dt)(lnNa⁺)计算得出的卵母细胞中Na⁺外流的速率常数仅约为根据(d/dt)[(ln(dNa⁺)/dt)]计算得出的速率常数的52%。这种差异可以通过假设卵母细胞内48%的Na⁺要么与蛋白质结合，要么被隔离在细胞器中来解释。
Na⁺外流的平均速率常数为6.4×10⁻³ min⁻¹，对应的表观Na⁺外流速率为13.3 p - 摩尔/cm²·秒。当对此进行微绒毛产生的表面积增加的校正后，真实的外流速率为1.1 - 1.3 p - 摩尔/cm²·秒。
哇巴因（1 - 5 μM）的作用似乎涉及两种不同的效应：（a）对膜Na⁺泵有48 - 65%的抑制作用，（b）细胞中一些被隔离的Na⁺被释放出来。
去除细胞外K⁺会使Na⁺外流减少40%，尽管由于从细胞中泄漏并可能保留在细胞表面附近的K⁺的存在，这个值可能被低估。
将细胞外K⁺浓度提高到15 mM可使哇巴因的抑制作用降低约一半。
得出的结论是，蟾蜍卵母细胞中的Na⁺泵活性水平可能略低于蛙肌肉中的，但它的一般特性与蛙肌肉和其他一些动物细胞中的相似。

Partition of sodium fluxes in isolated toad oocytes.