Effects of phenothiazines on low density lipoprotein metabolism in cultured human fibroblasts

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Abstract
Treatment of cultured human fibroblasts with trifluoperazine or chlorpromazine resulted in a biphasic effect on low density lipoprotein (LDL) catabolism, depending upon the dose. At up to 10−5 M, a marked increase in LDL binding, internalization and degradation was observed. This phenomenon took place within the first hours of incubation with the drugs, suggesting a direct effect on cell membrane physical characteristics, probably related to the lipophilic properties of phenothiazines. Concentrations above 2 × 10−5 M resulted in a relative decrease in LDL binding and internalization, and in a dramatic decrease in LDL degradation, which may be related to an inhibition of calmodulin‐dependent processes.