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

The membrane dipole potential (psi(d)) 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 psi(d) of 270 (+/- 20) mV over the course of 1 hour. In the presence of 0.4 mM cumene hydroperoxide there was an increase in psi(d) of 14 (+/- 7)%, accompanied by a decrease in cell diameter of similar to 14 (+/- 2)%. Exposure of the cells to 0.4 mM hydrogen peroxide caused psi(d) 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 similar to 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. (C) 2013 Elsevier B.V. All rights reserved.