The Biological Action of Ions and the Concentration of Ions at Surfaces

In this paper a new approach is made to the problem of the biological action of ions, particularly to the large class of antagonistic or balanced actions such as the antagonistic action of sodium and calcium which is important in determining cell permeability, in the behaviour of the heart, in the survival of marine organisms in artificial media, for the optimum development of plants, etc. In these balanced actions it is common for the action of one calcium ion to be balanced by the action of 50-100 sodium ions.f It is very difficult to see what kind of physicochemical mechanism can enable one calcium ion to offset the action of 25 or more sodium ions. The modern theory of strong electrolytes in homogeneous aqueous solution has completely failed to provide any clue for the solution of this problem. However, the situation would be much simplified if it could be shown that at the actual site of action of the ions the ionic ratio is not of the order of 50:1, as in the environmental fluid, but more nearly approaches 1:1.