Cholesteryl ester accumulation in smooth muscle cells after uptake of necrotic products from atherosclerotic lesions.
Cholesterol-ladened plasma membrane vesicles were used to load smooth muscle cells (SMC) with cholesterol. Plasma membrane vesicles (PMV) were isolated from rabbit atherosclerotic lesions, and characterized as to size, cholesterol content, and marker enzyme (plasma membrane, lysosome, endoplasmic reticulum) composition. PMV were regarded as a necrotic product since they are produced upon injury to cells. Degradation of PMV was proportional to the PMV protein concentration in the culture medium, suggesting bulk intake of PMV. Cholesterol accumulation of SMC varied with the cholesterol content of the vesicle. Incubation for 3 days with PMV having 0.39 and 0.62 mg cholesterol/mg protein induced the accumulation of 8 and 29 micrograms of esterified cholesterol/mg cell protein, respectively. Incorporation of oleate into cholesteryl ester during a 24-hr period under these conditions, however, was the same. The contribution of cholesterol ester synthesis to the esterified cholesterol content of SMC was 40 and 11% of the total when exposed to PMV having, respectively, low and high contents of cholesterol. This study suggests that cholesterol-bearing PMV in lesions can be utilized to load lesion-SMC. These observations suggest that lipid-bearing elements other than low density lipoprotein may be responsible for cholesterol-loaded SMC in lesions.
Hashimoto
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S
Research Service, Wadsworth Medical Center, Los Angeles, California 90073.
Wong
H
H
Blissard
D
D
Anderson
D
D
D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology; D001161:Arteriosclerosis / Q000378:metabolism* / Q000473:pathology; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology; D002499:Centrifugation, Density Gradient; D002788:Cholesterol Esters / Q000378:metabolism*; D006801:Humans; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D009336:Necrosis; D011817:Rabbits
D002788:Cholesterol Esters