Low density lipoprotein metabolism in the normal to moderately elevated range of plasma cholesterol: comparisons with familial hypercholesterolemia.
Low density lipoprotein (LDL) metabolism was investigated using a pulse injection of 125I-labeled LDL in 20 subjects who did not have familial hypercholesterolemia (FH) (plasma cholesterol 160-297 mg/dl) and in 9 subjects who did have heterozygous FH (plasma cholesterol 273-501 mg/dl). Subjects were also injected with 131I-labeled LDL chemically modified with cyclohexanedione. This technique permitted a calculation of the amount of apoLDL removed via receptor-mediated and receptor-independent pathways. In subjects without FH, 40% (range 25-49%) of LDL was cleared via receptor-mediated pathways and in subjects with FH this figure was 22% (range 3-33%). In nonfamilial hypercholesterolemia there was clear evidence of defective removal of LDL via receptor-independent pathways in association with some overproduction of apoLDL. In heterozygous FH there was evidence of defective removal of LDL via receptor-mediated pathways, while some subjects also showed evidence of overproduction of apoLDL. It is suggested that LDL catabolism via receptor-independent pathways plays a major role in regulating plasma cholesterol levels in the normal to moderately elevated range.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D005260:Female; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D002784:Cholesterol