Development of a novel method to determine very low density lipoprotein kinetics.
Isotopic tracer methods of determining triglyceride-rich lipoprotein (TRL) kinetics are costly, time-consuming, and labor-intensive. This study aimed to develop a simpler and cost-effective method of obtaining TRL kinetic data, based on the fact that chylomicrons compete with large VLDL (VLDL(1); S(f) = 60-400) for the same catalytic pathway. Ten healthy subjects [seven men; fasting triglyceride (TG), 44.3-407.6 mg/dl; body mass index, 21-35 kg/m(2)] were given an intravenous infusion of a chylomicron-like TG emulsion (Intralipid; 0.1 g/kg bolus followed by 0.1 g/kg/h infusion) for 75-120 min to prevent the clearance of VLDL(1) by lipoprotein lipase. Multiple blood samples were taken during and after infusion for separation of Intralipid, VLDL(1), and VLDL(2) by ultracentrifugation. VLDL(1)-apolipoprotein B (apoB) and TG production rates were calculated from their linear increases in the VLDL(1) fraction during the infusion. Intralipid-TG clearance rate was determined from its exponential decay after infusion. The production rates of VLDL(1)-apoB and VLDL(1)-TG were (mean +/- SEM) 25.4 +/- 3.9 and 1,076.7 +/- 224.7 mg/h, respectively, and the Intralipid-TG clearance rate was 66.9 +/- 11.7 pools/day. Kinetic data obtained from this method agree with values obtained from stable isotope methods and show the expected relationships with indices of body fatness and insulin resistance (all P < 0.05). The protocol is relatively quick, inexpensive, and transferable to nonspecialist laboratories.
Al-Shayji
Iqbal A R
IA
Department of Vascular Biochemistry, University of Glasgow, Glasgow, United Kingdom.
Gill
Jason M R
JM
Cooney
Josephine
J
Siddiqui
Samira
S
Caslake
Muriel J
MJ
D000328:Adult; D001055:Apolipoproteins B / Q000097:blood; D002914:Chylomicrons / Q000378:metabolism; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007700:Kinetics; D008079:Lipoproteins, VLDL / Q000097:blood*; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
D001055:Apolipoproteins B; D002914:Chylomicrons; D005217:Fat Emulsions, Intravenous; D008079:Lipoproteins, VLDL; D014280:Triglycerides