IONIC SEMIPERMEABILITY AS A BULK PROPERTY

Abstract

One of the most fundamental facts of biology is the unequal distribution of K+ and Na+ in and outside the cell, K+ being found in a relatively high concentration inside and Na+ outside. This unequal distribution has been attributed to the function of the cell membrane, to its selective permeability and "pumping action." No generally accepted picture has yet been developed for the mechanism of this hypothetical activity of the membrane, so it seems justifiable to consider alternate possibilities. A theory which pictures the ionic semipermeability of cells as a bulk property, (while earlier theories ascribed semipermeabllity to the "membrane" only), suggests experiments and calculations to demonstrate: the deranging activity of Na+ and the inactivity of K+; the preference of biological structures for K+ in the absence of a membrane; and whether the dipole forces of water are sufficient to account for the known distribution of K+ and Na+ in biological material. The experiments and calculations described give support to such a theory.