Abstract
We compared the in vivo metabolism of prebeta HDL particles isolated by anti-human apolipoprotein A-I (apoA-I) immunoaffinity chromatography (LpA-I) in human apoA-I transgenic (hA-I Tg) mice with that of lipid-free apoA-I (LFA-I) and small LpA-I. After injection, prebeta LpA-I were removed from plasma more rapidly than were LFA-I and small LpA-I. Prebeta LpA-I and LFA-I were preferentially degraded by kidney compared with liver; small LpA-I were preferentially degraded by the liver. Five minutes after tracer injection, 99% of LFA-I in plasma was found to be associated with medium-sized (8.6 nm) HDL, whereas only 37% of prebeta tracer remodeled to medium-sized HDL. Injection of prebeta LpA-I doses into C57Bl/6 recipients resulted in a slower plasma decay compared with hA-I Tg recipients and a greater proportion (>60%) of the prebeta radiolabel that was associated with medium-sized HDL. Prebeta LpA-I contained one to four molecules of phosphatidylcholine per molecule of apoA-I, whereas LFA-I contained less than one. We conclude that prebeta LpA-I has two metabolic fates in vivo, rapid removal from plasma and catabolism by kidney or remodeling to medium-sized HDL, which we hypothesize is determined by the amount of lipid associated with the prebeta particle and the particle's ability to bind to medium-sized HDL.
Highlights
We compared the in vivo metabolism of pre HDL particles isolated by anti-human apolipoprotein A-I immunoaffinity chromatography (LpA-I) in human apoA-I transgenic mice with that of lipid-free apoA-I (LFA-I) and small LpA-I
The phosphorimager analysis of these gels demonstrated that the LpA-I pools were relatively homogeneous in size (Fig. 1B; more than 90% of radiolabel in small LpA-I is in the 7.2 nm particles), and more than 90% of the radiolabel was found in the apoA-I region (28 kDa) (Fig. 1C)
The purpose of this study was to compare the in vivo metabolism of plasma pre LpA-I with that of LFA-I and small LpA-I particles
Summary
We compared the in vivo metabolism of pre HDL particles isolated by anti-human apolipoprotein A-I (apoA-I) immunoaffinity chromatography (LpA-I) in human apoA-I transgenic (hA-I Tg) mice with that of lipid-free apoA-I (LFA-I) and small LpA-I. We conclude that pre LpA-I has two metabolic fates in vivo, rapid removal from plasma and catabolism by kidney or remodeling to medium-sized HDL, which we hypothesize is determined by the amount of lipid associated with the pre particle and the particle’s ability to bind to medium-sized HDL.—Lee, J-Y., L. HDLs are a heterogeneous mixture of particles that form discrete subclasses [5,6,7] These subclasses can be separated on the basis of density [5], size [6], apolipoprotein content [8], and electrophoretic mobility [9]. Several different apolipoproteins can occupy the surface of HDL particles, apolipo-
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