Effects of chronic and acute lead treatments on the biophysical properties of erythrocyte membranes, and a comparison with model membranes

• The biophysical effects of lead on model and biomembranes have been examined.
• There is a positive correlation between acute and chronic treatments.
• Acute responses require lead doses 2–3 orders of magnitude higher than in chronic treatments.
• Lead increases membrane permeability, or hemolysis.
• Lead increases membrane microviscosity, or acyl chain molecular order.

Rat erythrocytes, or erythrocyte membrane ghosts, have been subjected to either chronic (drinking water containing 15 mM lead acetate for 3 months) or acute (10−9–10−2 M lead acetate for 1 h) Pb2+ treatments and subsequent changes in membrane properties have been measured. Pb2+ concentration in chronically treated rat plasma was 1.8 μM, which is one order of magnitude above normal values. Membrane permeability, or hemolysis, was increased in both cases. A comparative study using liposomes, in the form of large unilamellar vesicles, also indicated an increase in membrane permeability. Membrane microviscosity, or acyl chain molecular order, measured as DPH fluorescence polarization, showed an increased order in the acute treatments, at least below 700 μM Pb2+, and a similar increase in chronically treated rats. The correlation between acute and chronic treatments, and between cell and model membranes, suggests that the present observations may be relevant in the pathogenesis of lead intoxication in humans.