Arsenite, arsenate and vanadate affect human erythrocyte membrane

Abstract

Effects of arsenite, arsenate and vanadate on human erythrocyte membrane have been assessed according to their routes passing through the membrane, their binding modes to the membrane and their influences on membrane proteins and lipids. The uptake of arsenate (1.0 mM) by cells approached a limit with intracellular arsenic of about 0.2 mM in 5 h, and was strongly inhibited (;95%) by 4,49-diisothiocyano-2,29-disulfonic stilbene (DIDS), indicating that arsenate, similar to vanadate, passed across the membrane through the anion exchange protein, band 3. Arsenite (1.0 mM) influx reached a maximum of about 0.4 mM in 30 min, and was not inhibited by DIDS. The transformed species of arsenite bound to the membrane from cytosol. In contrast, arsenate bound rapidly from the outside, followed by releasing and re-binding. The binding to the membrane via sulfhydryl was indicated by the decrease of the sulfhydryl level of membrane proteins. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE) analysis revealed that the proteins, bands 1-3, were among the targets of arsenite, arsenate and vanadate. Their binding to the membrane also induced changes in the fluidity of membrane lipids and in the negative charge density in the outer surface of the membrane. q2000 Elsevier Science Inc. All rights reserved.

Influence of PAMAM dendrimers on human red blood cells

“…The surface of a normal erythrocyte is negatively charged due to the presence of glycolipids and some glycated integral and peripheral proteins. Electrostatic repulsion among red blood cells prevents their self-aggregation and adhesion to the walls of blood vessels [7]. Cationic PAMAM dendrimers come close to the red blood cell surface as a result of electrostatic attraction.…”

Oxidative Balance in Brain After Exposure to Arsenic in Ex Vivo and in Vivo Models.

“…The conjugation of iAs III with GSH has been described by Hayakawa et al (2005) and Pastore et al (2003). Since As interacts with thiol groups, it can be directly toxic by blocking essential sulfhydryl groups of protein and enzymes, such as succinic and pyruvate dehydrogenases (Aposhian, 1989), or by binding to free sulfhydryl groups of membrane proteins inducing a marked decrease of free sulfhydryl groups and altering the intracellular signaling mechanisms (Zhang et al, 2000). DMAG III was described to be reduced to a dimethylarsine by a GR and NADPH, and this product may react with molecular O 2 to form dimethylarsine radical.…”

Zinc protects against arsenic-induced apoptosis in a neuronal cell line, measured by DEVD-caspase activity

“…The highly charged, hydrophilic ion Zn ++ does not cross biological membranes as easily and the entry of zinc is determined by the availability and concentration of membrane-spanning zinc transport proteins (Kambe et al 2004). In contrast to arsenic, zinc may be lost easily from within the cell, as it is not tightly bound inside the cell, but labile (Cousins 1986) while arsenic is highly reactive, binding to sulfhydryl groups in intracellular and membrane proteins (Menzel et al 1999;Zhang et al 2000).…”