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TIME DEPENDENCE OF ACCUMULATION AND BINDING OF INORGANIC AND ORGANIC ARSENIC SPECIES IN RABBIT ERYTHROCYTES
Citation:
Delnomdedieu, M., M. Styblo, AND D. Thomas. TIME DEPENDENCE OF ACCUMULATION AND BINDING OF INORGANIC AND ORGANIC ARSENIC SPECIES IN RABBIT ERYTHROCYTES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/560, 1995.
Description:
The uptake by rabbit erythrocytes of 0.4 mM arsenite, As(III), arsenate, As(V), monomethylarsinate, MMA(V) and dimethylarsonate, DNM(V) were compared over 24 hours. n membrane-free hemolysate, the protein-to-cytosol ratio was determined by ultrafiltration and arsenic species were identified by thin layer chromatography methods. 1H spin-echo Fourier transform NMR was used to follow the binding of arsenic species to glutathione (GS H). 1P-NMR was used to observe their effects on high-energy adenine nucleotide levels (e.g. ATP, ADP). hese results demonstrate that As([H) readily accumulates in cells, reaches a quasi-plateau at 78% of the As in the incubation system after I hour and at 88% after 24 h. On average, 20% of the told erythrocyte As(III) burden is associated with the protein fraction (e.g. hemoglobin, Hb). bout 68% of the As(III) burden is bound to GSH. S(III) has no effect on ATP levels during a 5h incubation. s(V) enters erythrocytes slowly (53% after 5h). owever, erythrocytes take up 81 % of the As(V) in the reaction system after a 24h incubation. f the total As burden in As(V)-exposed cells, 22% was associated with the proteins and possibly reduced to AS(III) and 59% was in the ultrafiltrate (8% as As(III) and 51% as As(V)). his finding indicates that over a 24 h incubation, the reduction of As(V) to As(III) may account for 30% of the total As in rabbit erythrocytes. s(V) present in the erythrocytes enters the phosphate pool and depletes ATP. n comparison, about 65% of the total MMA(V) and about 44% of the total DMA(V) in the incubation system are taken up by rabbit erythrocytes during a 24h incubation. either organoAs species pe the Hb signals observed by spin-echo Fourier transform NNM and the binding to GSH was minimal. nlike As(V), MMA(V) and DMA(V) do not perturb phosphate metabolism, showing that, despite their pentavalent oxidation state, these arsenic species are not analogs for phosphate.