A method was developed for measuring the self-diffusioncoefficient of solutes in agar gel suspensions of red cells. Thepurpose was to investigate the influence of the red cell on thediffusion of ions which are important in blood solute transport.
The capillary diffusion method was employed. The diffusioncoefficient was calculated from the initial and final concentrationof tracer in the capillary. The results are discussedin terms of a modified Maxwell equation for the average conductivityin a granular medium in which a discontinuous boundarycondition is employed to account for the observed partitioncoefficients.
The results indicate the ration of the diffusivity of solutein the red cell suspension to that in the suspending mediumvaries considerably with the ion. This ratio is greater for sodium than for chloride over the range of red cell volumefractions investigated. An augmented diffusional mechanismfor bicarbonate appears to exist in the red cell suspension.Depleting the intracellular ATP has little effect on the diffusionof sodium in the red cell suspension.
