title: High-density lipoprotein apolipoprotein A-I kinetics: comparison of radioactive and stable isotope studies.
abstract: To compare the kinetic determinants of high-density lipoprotein (HDL) apolipoprotein A-I (apoA-I) concentration in lean normolipidaemic subjects using radioisotope and stable isotope studies. We pooled data from 16 radioisotope and 13 stable isotope studies to investigate the kinetics of apoA-I in lean normolipidemic individuals. We also examined the associations of HDL kinetic parameters with age, sex, body mass index (BMI) and concentrations of apoA-I, triglycerides, HDL cholesterol and low-density lipoprotein (LDL) cholesterol. Lean subjects from radioisotope and stable isotope studies were matched for age, gender, BMI and lipid profile. The apoA-I concentration was significantly lower in the radioisotope group than the stable isotope group (P = 0.031). There was no significant difference in HDL apoA-I fractional catabolic rate (FCR) and production rate (PR) between the groups. In the radioisotope group, HDL apoA-I FCR was significantly associated with apoA-I and HDL cholesterol concentrations (r = -0.681, P < 0.001 and r = -0.542, P < 0.001, respectively), whereas in the stable isotope group, only HDL apoA-I PR was significantly associated with apoA-I concentration (r = 0.455, P = 0.004). Our findings suggest that HDL apoA-I FCR is the primary determinant of apoA-I concentrations in lean subjects in studies using radiotracer techniques. By contrast, HDL apoA-I PR is the primary determinant of apoA-I concentration in lean subject in studies employing stable isotope methods. These discrepancies may be reconciled by differences in methodologies and/or study population characteristics.
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Western Australia, Australia.
authors.forename: E M M
authors.initials: EM
authors.lastname: Ooi
authors.forename: G F
authors.initials: GF
authors.lastname: Watts
authors.forename: M S
authors.initials: MS
authors.lastname: Farvid
authors.forename: D C
authors.initials: DC
authors.lastname: Chan
authors.forename: M C
authors.initials: MC
authors.lastname: Allen
authors.forename: S R
authors.initials: SR
authors.lastname: Zilko
authors.forename: P H R
authors.initials: PH
authors.lastname: Barrett
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D016632:Apolipoprotein A-I / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007554:Isotopes; D007930:Leucine; D008075:Lipoproteins, HDL / Q000378:metabolism / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014280:Triglycerides / Q000097:blood
chemical_list: D016632:Apolipoprotein A-I; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007457:Iodine Radioisotopes; D007554:Isotopes; D008075:Lipoproteins, HDL; D014280:Triglycerides; D007930:Leucine