The effect of possible inhibitors of fluid-phase pinocytosis on LDL uptake and net cholesterol accumulation in wild-type M-CSF-differentiated macrophages.

Wild-type bone marrow-derived macrophages were pretreated 1 h with drug vehicle or the indicated drug. For cholesterol accumulation, macrophages then were incubated with 1 mg/ml LDL and inhibitor for 6 h. For 125I-LDL uptake, macrophages then were incubated with 200 µg/ml 125I-LDL and inhibitor for 6 h. All incubations were performed in serum-free medium containing 50 ng/ml M-CSF. The percent inhibition of net cholesterol accumulation compares macrophages treated with LDL alone and LDL with inhibitor (except the experiment that compares macrophages treated with LDL and dynamin peptide inhibitor with LDL and control peptide) after basal cholesterol values were subtracted from each. The percent inhibition of 125I-LDL uptake compares macrophages treated with 125I-LDL alone and 125I-LDL with inhibitor. Control values for macrophages incubated with LDL alone or 125I-LDL alone are indicated in parentheses. For cholesterol accumulation, control values are expressed as nmol net cholesterol accumulation/mg cell protein. For 125I-LDL uptake, control values are expressed as µg 125I-LDL uptake/mg cell protein. The range of cell-associated and degraded 125I-LDL for all treatments except bafilomycin A1-treated macrophages was 15–19% and 82–86%, respectively. Cell-associated and degraded 125I-LDL for bafilomycin A1-treated macrophages was 91% and 9%, respectively. * = ppp