Effect of chromate ion on the membrane of established human cells as measured by uptake of a permeant lipophilic cation.

Cells from the established human cell line NHIK3025 concentrate the permeant lipophilic cation triphenylmethylphosphonium (TPMP+) against a concentration gradient, indicating the existence of an electrical potential across the cell membrane (interior negative). Cells exposed to potassium chromate or dichromate (7.7 mumol Cr/l) for 2 h subsequently showed reduced uptake of TPMP+, whereas similar exposure to a trivalent chromium salt (7.7 mumol/l chromic chloride) had similar uptake of TPMP+ as control cells. These preliminary results suggest that a primary effect of chromate on these cells is to reduce the electrical potential across the cell membrane.