Determination of human erythrocyte membrane hydraulic conductivity

Abstract

A method of determining the osmotic water permeability of red cell membranes is described. This method is based on the rate of cell volume change induced by the perturbation of the osmotic environment of the cells and the paralleling change in light scattering by the cells. The method requires as little as 0.3 ml of blood and utilizes commercially available equipment. The value for the hydraulic conductivity of the human red cell membrane determined by this new technique is 1.56 ± 0.04 x 10 -11 cm 3/dyne sec, in good agreement with other techniques. These studies show that the hydraulic conductivity of the human erythrocyte membrane does not depend on the degree cell volume change when the cells are shrunk from their isotonic volume by 15, 20, or 25%. However, the Lp increases 50% when the cells are swollen 25%. The small amounts of blood required and the ready availability of the equipment necessary for the technique makes it now possible for many laboratories to make Lp determinations on normal or abnormal erythrocyte membrane as a means of more fully describing the permeability properties of the cell membrane.