ESTERIFICATION OF CHOLESTEROL IN RAT-TISSUES AND ALTERATION OF THE APOLIPOPROTEIN SPECTRUM IN THE ANIMAL BLOOD-PLASMA IN PRESENCE OF AUTOXIDIZED CHOLESTEROL

Influence of autooxidized cholesterol (Ch) products on accumulation of cholesterol esters (ChE) in liver and aorta tissues as well as alteration of the apolipoprotein spectrum in low density and very low density (LDL and VLDL) lipoproteins in blood plasma was studied in rats treated with purified Ch (ChP-rats) and with oxidized Ch containing 5% 25-hydroxyCh and 3% 7-ketoCh (ChO-rats). Increase of ChE content in liver tissue of ChO-rats resulted in two-fold activation of acyl-CoA-cholesteral-O-acyltransferase (ACAT) in liver microsomes as compared with the enzymatic activity rate in ChP-rats. As shown by polyacrylamide gel electrophoresis content of apoE in VLDL and LDL of ChO-rats was 1,5-fold higher as compared with that of ChP-rats. Content of apoIV was increased in LDL and VLDL of ChP-rats as compared with controls; this effect was not observed in ChO-rats. LDL and VLDL from ChO-rats stimulated incorporation of C-14-oleate into ChE of cultivated macrophages. Increase in content of ChE found in aorta of ChO-rats appears to occur due to activation of Ch esterification. Intensification of ChE synthesis in tissues and alterations in the spectrum of LDL and VLDL apolipoproteins caused by oxidized products of cholesterol may be one of the mechanisms involved in atherogenesis.