Lipid metabolism by rabbit aortic intimal and medial cells in tissue culture.

Abstract

Aortic cells from intimal and medial layers of aortas from both normal and cholesterol-fed rabbits were studied in tissue culture. Three preparations from normal-fed rabbits were used—intimo medial cells prepared either from explants or from collagenase, elastase digests of the inner aortic layer and cells prepared from explants of the medial muscle layer. Two preparations from cholesterol-fed rabbits—collagenase, elastase digests of the inner aortic layer and cells from the medial layer were used. Growth was rapid in secondary cultures prepared from enzyme digests and the cells could be used for isotope uptake and incorporation studies within seven days of primary seeding. Growth from medial explants was slower but secondary cultures were readily prepared and could be used for isotope studies. All five preparations took up appreciable amounts of (1-14C)-oleic acid and incorporated this precursor primarily into phospholipid (mostly lecithin and phosphatidyl inositol). A smaller proportion of the label was incorporated into triglyceride but only about 3% was incorporated into cholesteryl ester by each of the five cell types studied. A significantly greater proportion of the (1-14C)-oleic acid was incorporated into triglyceride and a lower proportion incorporated into phospholipid by the intimal cells from the cholesterol-fed rabbit than was the case with the intimal cells from the normal-fed rabbit. No other differences in incorporation of the oleic acid into other lipid fractions was demonstrated between the five cell preparations studied. The uptake and incorporation of 32P-phosphate into phospholipid by the five cell preparations was also demonstrated. Cells grown from intimal digests of the cholesterol-fed rabbit aortas showed significantly lower incorporation into phosphatidyl inositol and higher incorporation into lecithin than the other cell preparations. The synthesis of lipid by normal and cholesterol-fed rabbit aortic cells in relation to the pathogenesis of atherosclerosis is discussed.