LEAD TRANSPORT IN IEC-6 INTESTINAL EPITHELIAL-CELLS

This study evaluated the use of IEC-6 cells as a model for studying le ad (Pb) transport by intestinal epithelial cells (IECs) and examined p otential transport mechanisms for Pb uptake and extrusion. Pb accumula tion in IEC-6 cells exposed to 5 and 10 mu M Pb for up to 60 min was t ime-and dose-dependent. Reduction of incubation temperature significan tly reduced the total cellular Pb content of IEC-6 cells. Simultaneous exposure of cells to zinc (Zn) and Pb resulted in decreased total cel lular Pb contents compared to total cellular Pb contents of cells expo sed to Pb only. IEC-6 cells treated with ouabain (1 mM) or sodium azid e (1 mM) and 5 mu M Pb accumulated more Pb than cells exposed to Pb on ly. Cells treated with p-chloromercuribenzensulfonic acid (50 mu M), p -chloromercuribenzoic acid (50 mu M), or iodoacetimide (50 mu M) accum ulated less Pb than cells treated with Pb only. We conclude that Pb up take by IEC-6 cells depends on the extracellular Pb concentration. Our data suggest that the mechanism of Pb uptake by IECs is complex, and that Pb transport in IEC-6 cells is time-and temperature-dependent, in volves sulfhydryl groups, and is decreased by the presence of Zn. Extr usion of Pb is at least partially dependent on metabolic energy.