Diffusion of sucrose, sodium, and water in ventricular myocardium

Abstract

Fundamental to the analysis of capillary-tissue exchanges is a knowledge of tissue transfer rates by diffusion outside the capillaries (2, 30). The purpose of this work was to determine the apparent tissue diffusion coefficients for sucrose, sodium, and water at body temperature in the cat myocardium. The studies were made in a diffusion cell (32) on a sheet of cat myocardium by a method modified from that described by Page and Bernstein (26). These authors found at 23°C that sodium did not enter the cells and that the steady-state diffusion of water, sodium, and sucrose could be accounted for by fluxes occurring only in the extracellular space. Since cell membrane permeability to water is so high that restriction of water diffusion to the extracellular space seemed unlikely, we felt that a study of the three tracers simultaneously at 37°C was needed.