Effect of chlorpromazine on lipid metabolism in aortas from cholesterol-fed rabbits and normal rats, in vitro: Inhibition of sterol esterification and modification of phospholipid synthesis

Chlorpromazine (CPZ), a major tranquilizer, was found to be a potent inhibitor of acylCoA:cholesterol acyltransferase (ACAT, EC 2.3.1.26) in isolated arterial microsomes and in intact arterial tissue from the rat and cholesterol-fed rabbit in vitro. In isolated rabbit arterial microsomes, CPZ resulted in a concentration-dependent inhibition of ACAT with 50% inhibition of 1-¹⁴C]oleoylCoA incorporation into ¹⁴C]cholesteryl esters occurring at 0.1 mM CPZ. CPZ also effectively inhibited the incorporation of ¹⁴C]oleate into triglycerides without affecting incorporation into diglycerides. Additionally, CPZ altered the pattern of arterial phospholipids synthesized from 1-¹⁴C]oleate. Incorporation into phosphatidylcholine was depressed while incorporation into phosphatidylinositol was increased. Since diglyceride synthesis appreared to be unaffected by CPZ, a redirection of phosphatidic acid into the CDP-diglyceride pathway of glycerolipid synthesis does not adequately account for the effect of CPZ on arterial phospholipid and triglyceride synthesis in these experiments.