Electrokinetic properties of dissociated chick embryo cells. I. Ph‐surface charge relationships and the effect of calcium ions

Abstract

Since the electrokinetic properties of a particle depend entirely upon the particle's surface, microscopic electrophoresis of dissociated cells can yield information about the cellular surfaces. Dissociated heart ventricle and liver cells from five‐day chick embryos as well as neural retinal cells from seven‐day embryos have been examined electrophoretically over a wide pH range and the pH‐net surface charge density relation for each type of cell has been determined. Under the conditions selected the cells show differences with respect to these relations which appear to reflect differences in the molecular composition of the cells' surfaces.Since intercellular adhesion may occur through bivalent cation bridges with calcium being the cation most likely to be involved, the suppression of surface charge density by means of calcium ions at physiological concentration has been determined at physiological pH for heart ventricle, liver, neural retinal, and back epidermal cells. The degree of charge suppression, which varies among cells of different types, can be correlated with the apparent cellular adhesiveness as judged from sorting out behavior in some but not all cases.Dye exclusion, the ability of cells removed from the electrophoresis apparatus to reaggregate, and the reversibility of pH effects and calcium effects have been used to try to detect damage to the cells caused by experimental conditions. The results of these tests have seemed satisfactory.