Chromate effects on human erythrocytes--investigations on sulphydryl groups, cross-linking of membrane proteins and electromechanical properties in the coulter-counter.

The carcinogen chromate inactivates its own carrier in the human erythrocyte membrane. This effect is paralleled by the inhibition of chromate uptake by the sulphydryl reagents N-ethylmaleimide and iodoacetate. However, no decrease in the sulphydryl content of erythrocyte membranes treated with up to 100 mM chromate was detected. By SDS gel electrophoresis, a limited cross-linking of red cell membrane proteins was found at 100 mM chromate, but not at cytotoxic concentrations up to 10 mM chromate. Erythrocytes treated with up to 100 mM chromate exhibited no change in the "dielectric breakdown", i.e. the sharp decrease of the apparent cellular volume at a critical detector current.