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 eIectrophoresis 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.

Intercellular adhesion: Modification by dielectric properties of the medium

“…The results show that the calculated zeta potentials in both the experimental and control media are very similar and agree well with the values quoted in the literature for these cell types measured in simple saline solutions (Collins, 1966;Curtis, 1967). It is therefore concluded that with none of the compounds used in cell aggregation studies does any significant adsorption to the cell surface occur, since on adsorption large changes in zeta potential would be predicted (Abramson, Moyer & Gorin, 1942).…”

“…This is in good agreement with other figures quoted in the literature. Both 7-day neural retina and 5-day limb bud suspensions were examined under identical conditions of applied voltage (50 V) and temperature (2.5 ~ Cell mobilities were observed and zeta potentials calculated using the Helmholtz-Smoluchowski equation (Collins, 1966). The results are given in Table 4.…”

Palmitate uptake by neonatal rat myocytes and hepatocytes

“…At the outer cell membrane leaflet, polar groups such as phospholipids and glycoproteins exist in various states of ionization. At physiological pH, most of these polar groups are negatively charged [23,24] (also see [25,26]). An increased charge density in neonatal heart ventricular cells and liver cells has been reported to occur between pH 4 and 9, with hepatocytes showing a much greater charge density than cardiac myocytes [23].…”

Polycations and cationic lipids enhance adenovirus transduction and transgene expression in tumor cells

“…17 Through empirical experimentation, investigators have concluded that polycationic compounds added during virus adsorption diminish electrostatic repulsion between negatively charged mammalian cells and eucaryotic viruses. 13,18 Viruses reported to benefit from polycation addition include herpes virus, echovirus, Rous sarcoma virus, orthomyxovirus, and an adenovirus. 12 When prepared in the proper charge ratios, poly(L)-lysine forms noncovalent complexes with adenovirus vectors 19 to produce a net positive charge that may favor adenovirus-cellular interactions.…”