Ling G N
Physiol Chem Phys. 1980;12(3):215-32.
A new method permits, in a complex efflux curve from living cells, identification of the fraction of labeled solute rate-limited by intracellular-extracellular exchange. Using this method, it was found that in Na+ efflux from frog voluntary muscle, the slow fraction conventionally described as rate-limited by membrane permeability is wrongly assigned. Instead, a much faster fraction, usually camouflaged by the efflux of labeled Na+ in the extracellular space, represents the exchange of intra- and extracellular Na+ rate-limited by cell surface permeation. Quantitatively, the result shows that the Na+ permeability constant has up to now been underestimated by a factor of 10. Implications of that finding for the theory of the resting potential, and the minimum energy required of resting frog muscles, are discussed.
一种新方法能够在活细胞复杂的流出曲线中，识别出受细胞内外交换限速的标记溶质部分。使用该方法发现，在青蛙随意肌的钠离子流出过程中，传统上被描述为受膜通透性限速的缓慢部分被错误归类。相反，一个通常被细胞外空间中标记钠离子流出所掩盖的快得多的部分，代表了受细胞表面渗透限速的细胞内和细胞外钠离子交换。从数量上看，结果表明钠离子通透性常数到目前为止被低估了10倍。讨论了这一发现对静息电位理论以及青蛙静息肌肉所需最小能量的影响。
