The influence of chlorpromazine on the potential-induced shape change of human erythrocyte

Chlorpromazine modulates the morphological macro- and microstructure of endothelial cells

Chlorpromazine (CP), an amphipathic, antipsychotic agent, causes concave membrane bending in red blood cells with formation of stomatocytic shapes by modulation of the phospholipid bilayer. This study was designed to investigate the effects of CP on the shape of bovine aortic endothelial cells (BAEC) and their membranes in confluent monolayers with phase-contrast and transmission electron microscopy. Exposure of BAECs to nanomolar levels of CP leads to membrane curvature changes. With increasing CP concentrations, the membrane assumed a shape with enhanced numbers of intracellular caveolae and projection of pseudopodia at all junctions. At higher CP concentrations (up to 150 microM), the endothelial cells assumed almost spherical shapes. The evidence suggests that CP may affect lipid bilayer bending of BAECs in analogy with previous observations on erythrocytes, supporting the formation of caveolae and pseudopodia in BAECs due to the induction of concave membrane bending, as well as an effect on endothelial cell membrane adhesion at higher CP concentrations with loss of cellular attachment at junctions.

Membrane potential and human erythrocyte shape

Altered external pH transforms human erythrocytes from discocytes to stomatocytes (low pH) or echinocytes (high pH). The process is fast and reversible at room temperature, so it seems to involve shifts in weak inter- or intramolecular bonds. This shape change has been reported to depend on changes in membrane potential, but control experiments excluding roles for other simultaneously varying cell properties (cell pH, cell water, and cell chloride concentration) were not reported. The present study examined the effect of independent variation of membrane potential on red cell shape. Red cells were equilibrated in a set of solutions with graduated chloride concentrations, producing in them a wide range of membrane potentials at normal cell pH and cell water. By using assays that were rapid and accurate, cell pH, cell water, cell chloride, and membrane potential were measured in each sample. Cells remained discoid over the entire range of membrane potentials examined (-45 to +45 mV). It was concluded that membrane potential has no independent effect on red cell shape and does not mediate the membrane curvature changes known to occur in red cells equilibrated at altered pH.