Arterial repair and atherosclerosis after mechanical injury: Part 4. Uptake and composition of cholesteryl ester in morphologically defined regions of atherosclerotic lesions

Abstract

Atherosclerotic lesions with defined morphological properties were induced by mechanical trauma in the aorta of normo-lipidemic rabbits. In all parts of the lesion and regardless of the morphological distribution of the lipid, cholesteryl esters with mono-unsaturated fatty acids dominated, whereas cholesteryl esters with di-unsaturated fatty acids dominated in plasma. The similarity between the cholesteryl ester composition in non-endothelialized regions of the lesion and that in endothelialized regions suggests that the cholesteryl ester composition is primarily determined by local, cellular activity, independently of plasma influx. Twenty-four hours after the injection of tritiated cholesterol, no consistent differences between the specific activities in the three more saturated cholesteryl ester fractions were encountered, suggesting that both differential hydrolysis and differential esterification might contribute to the characteristic cholesteryl ester pattern of the lesions. The specific activity of cholesteryl esters with fatty acyl groups containing three or more double bonds was lower than that of other cholesteryl ester fractions, and the proportion of poly-unsaturated cholesteryl esters increased during restoration of the arterial wall structure, suggesting a slow removal of such esters. These results suggest that hydrolysis of cholesteryl esters may be a prerequisite for the elimination of cholesterol deposits from atherosclerotic lesions.