Effects of cholesterol content on the metabolism of protein-free emulsion models of lipoproteins.
After intravenous injection, emulsions with compositions similar to chylomicrons behaved metabolically as described for chylomicrons, with faster removals of triacylglycerols than cholesteryl esters from the blood after injection into rats, and with greater uptakes of cholesteryl esters than triacylglycerols by the liver. In contrast, emulsions with a high content of free cholesterol showed equal removal rates from the blood of triacylglycerols and cholesteryl esters; and similar uptakes by the liver. This pattern of metabolism was that expected for a chylomicron core remnant particle. Emulsions poor in cholesteryl ester but rich in free cholesterol showed remnant-like behavior, whereas emulsions rich in cholesteryl ester but poor in free cholesterol were metabolized like nascent chylomicron particles. The amount of free cholesterol appeared to regulate metabolism by affecting the binding of apolipoproteins to the particle surface. Emulsions with a high content of free cholesterol bound less A-I, A-IV and C apolipoproteins, and the relative amount of apolipoprotein E was increased. All of these effects are consistent with the metabolic differences between chylomicrons and remnant particles, suggesting that the amount of free cholesterol plays a regulatory role in chylomicron metabolism.
Maranhao
R C
RC
Tercyak
A M
AM
Redgrave
T G
TG
D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000378:metabolism; D001056:Apolipoproteins C / Q000378:metabolism; D001057:Apolipoproteins E / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D002914:Chylomicrons / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology; D004655:Emulsions; D004967:Estrogens / Q000494:pharmacology; D008074:Lipoproteins / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008854:Microscopy, Electron; D051381:Rats; D013010:Sonication; D013329:Structure-Activity Relationship; D014280:Triglycerides / Q000378:metabolism
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D001056:Apolipoproteins C; D001057:Apolipoproteins E; D002788:Cholesterol Esters; D002791:Cholesterol, Dietary; D002914:Chylomicrons; D004041:Dietary Fats; D004655:Emulsions; D004967:Estrogens; D008074:Lipoproteins; D014280:Triglycerides; C022205:apolipoprotein A-IV; D002784:Cholesterol