| Popis: |
Trivalent arsenic (As(III)) exposure is linked to cancer, but exposure includes pentavalent arsenic (As(V)). These forms interconvert in biological systems, and the mechanism is not understood. Arsenic has a high affinity for sulfhydryls, and the interaction of As(III) and As(V) with biological sulfhydryls and cellular uptake was investigated in this study. Incubation of rat blood at 1 mM arsenic showed As(V) uptake, membrane and protein binding to be time dependant. These processes were almost immediate with As(III) incubation. Incubation at 25 mM As(V) resulted in 40% thiol depletion with no oxidized glutathione formation. Metabolite analysis showed half of the As(V) converted to As(III). In As(III) incubation, 27% thiol depletion occurred with 300% increase in GSSG. As(V) reduction combined with thiol depletion could indicate that arsenate used sulfhydryls as reducing equivalents. Because arsenate uptake was slow this reduction may not be a main contributor to the overall in vivo process. |
