High-density lipoprotein apolipoprotein A-I kinetics: comparison of radioactive and stable isotope studies.
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.
Ooi
E M M
EM
School of Medicine and Pharmacology, University of Western Australia, Western Australia, Australia.
Watts
G F
GF
Farvid
M S
MS
Chan
D C
DC
Allen
M C
MC
Zilko
S R
SR
Barrett
P H R
PH
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
D016632:Apolipoprotein A-I; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007457:Iodine Radioisotopes; D007554:Isotopes; D008075:Lipoproteins, HDL; D014280:Triglycerides; D007930:Leucine