The copper-induced deformability loss and echinocyte formation in human erythrocytes: an electron paramagnetic resonance study.

The effects of incubating human erythrocytes with CuSO4 under prelytic conditions were investigated to clarify the cause of the decreased whole-cell deformability in flow, using electron paramagnetic resonance and the spin label methods. The effect of Cu(II) on erythrocytes was manifested by the dose-dependent echinocyte formation as well as by the decreased whole-cell deformability in flow. The deformability loss was attributed in part to the altered rheological characteristics due to echinocytosis. By using various reagents capable of reversing the effects of Cu(II) on morphology and deformability loss, it was shown that at least two types of damage sites can be distinguished. They include (1) the Cu(II) coordination sites which can be dissociated by chelating reagents and (2) the sites involving sulfhydryl groups in which disulfide bonds and probably Cu(II)-bridged strong coordination bonds are formed. The latter can be reversed by sulfhydryl reagents such as dithioerythritol, but not by EDTA or penicillamine. Pretreatment of erythrocytes with iodoacetate eliminates the variance in susceptibility to Cu(II) among donors and generally enhances the effects of Cu(II) by lowering the cellular glutathione level. A possible relation between the nature of the damage sites and the cellular glutathione level is discussed.