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MEDIA SERUM LEVELS AND IN VITRO HEPATIC ABSORPTION OF LINDANE
Citation:
Croom, E. L. AND R. A. PEGRAM. MEDIA SERUM LEVELS AND IN VITRO HEPATIC ABSORPTION OF LINDANE. Presented at Society of Toxicology (SOT) Annual Meeting, Washington, DC, March 06 - 10, 2011.
Impact/Purpose:
Experiments were conducted to determine the cellular uptake of lindane in vitro under different conditions
Description:
High plasma protein binding is known to reduce the tissue uptake of chemicals in vivo, but the extent of its importance in vitro is less clear. Experiments were conducted to determine the cellular uptake of lindane in vitro under different conditions. Lindane was selected because of its high plasma protein binding, ~90%, and low limit of detection. In vitro assay conditions commonly range from 0 to 20% serum but sometimes involve media containing 75% to 100% serum. In vitro dosing schedules for viable cells often extend to 24hrs before the media is changed. Rat hepatocytes in 12 well plates were exposed to 1uM lindane. Media was supplemented with fetal calf serum (FCS). FCS levels were varied and media contained 0%, 5%, 20%, 50%, 75% or 100% FCS. After incubation, lindane was hexane extracted from tissue and media. At 24 hrs the highest concentrations of lindane were found in hepatocytes cultured in 100% FCS, while the lowest concentrations were found in hepatocytes cultured in serum-free media. In wells containing the lowest serum concentrations, very little lindane was recovered from the media or cells, suggesting the unbound lindane was absorbed and metabolized. Human liver slices (20 mg) were used under similar conditions but in the absence of a regenerating systemtolimitthe loss of lindane through metabolism. At 5 minutes, most of the lindane was present in the liver slices, with the highest concentrations found in tissue in serum-free media. At 24 hrs, the greatest concentrations of lindane were in tissues with low serum concentrations and the lowest levels of lindane were found in tissues in 100% FCS. Taken together, these results suggest that at low chemical concentrations high serum levels can delay the entry of lindane into tissue in vitro. In systems with high metabolic capacity this limited availability would likely extend the in vitro half-life ofa compound. (This abstract does not necessarily reflect U.S. EPA policy).