Permeability of Muscle Cells

Abstract

SINCE the advent of artificial radioactive elements, a considerable amount of work on the exchange of labelled ions or molecules against unlabelled ones of the same chemical nature has been carried out on biological material. Krogh has reviewed¹ a number of applications of the technique to exchanges between living cells and their surroundings, and Using² reports results obtained for the exchange of sodium between isolated muscle and Ringer solution. The remarks made by A. V. Hill³ concerning measurements of so-called permeability of tissues appear to have been overlooked. He emphasized that diffusion might play the most important part in determining the rate of transfer of dissolved substances from lymph to tissue, even when the size of the tissue is only that of, say, a frog sartorius muscle. It appears, therefore, necessary when attempting to study cell-wall permeability either to use single cells, or to make allowance for the effect of diffusion being the means by which the extra-cellular fluid comes into eventual equilibrium with the fluid surrounding the assembly of cells. Experiments made in vivo will be less affected by the retarding influence of diffusion than will those made in vitro. This is because in the former case the blood-flow through the capillaries brings the substance being investigated into the interior of the tissue.