The effect of oxidative stress on the membrane dipole potential of human red blood cells

The membrane dipole potential (ψd) is an important biophysical determinant of membrane function and a sensitive indicator of lipid organisation. In this study we have used the environmentally sensitive probe di-8-anepps to explore the effects of oxidative stress on the membrane dipole potential of human erythrocytes. Cells suspended in 0.15 mM phosphate buffered saline containing 0.1 mg/ml albumin maintained a mean value for ψd of 270 (± 20) mV over the course of 1 hour. In the presence of 0.4 mM cumene hydroperoxide there was an increase in ψd of 14 (± 7)%, accompanied by a decrease in cell diameter of ~ 14 (± 2)%. Exposure of the cells to 0.4 mM hydrogen peroxide caused ψd to decrease by 13 (± 8)% at the centre of the cell and 8 (± 5)% at the edge whilst the diameter remained constant. In both cases the changes were equivalent to a change in transmembrane electric field of a magnitude of ~ 10 MVm− 1, sufficient to influence membrane function. Raman microspectrometry supported the conclusion that cumene exerts its effect primarily on membrane lipids whilst hydrogen peroxide causes the formation of spectrin–haemoglobin complexes which stiffen the membrane.

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► The membrane dipole potential varies with curvature in normal red blood cells
► Effect of oxidative stress on membrane dipole potential is dependent on ROS present
► Hydrogen peroxide causes cell stiffening and decreased membrane dipole potential
► Cumene hydroperoxide causes cell shrinkage and increased membrane dipole potential