MODULATION OF MEMBRANE CHOLESTEROL CONTENT IN CULTURED LLC-PK1 CELLS

This study was designed to develop a cell culture model to evaluate th e effect of cell membrane fluidity on the function of drug carrier pro teins. Fluidity of the cell membrane has been linked to its cholestero l content. LLC-PK1 cells were grown as a monolayer and were treated wi th a BSA-PVP-cholesterol complex in time-dependent studies. The total cholesterol content of the cells was increased 4-fold (from 52 to 200 fmol/mg protein) as a result of this treatment. The cholesterol increa se appears to level off at 2 h of treatment. Most of the incorporated cholesterol (77%) was determined to be free cholesterol, the rest bein g esterified. Membrane fractions of the treated cells were isolated an d were determined to carry 88% of the cholesterol content. The studies indicate that it is feasible to deliver cholesterol to cultured epith elial cells and that LLC-PK, cell monolayers can be used as a model fo r such studies.