Journal of Lipid Research, Vol 26, 210-217, Copyright © 1985 by Lipid Research, Inc.
Role of very low density lipoproteins in the energy metabolism of the rat
RR Wolfe and MJ Durkot
The role of very low density lipoproteins (VLDL) in the energy metabolism
of conscious, 24-hr fasted rats was studied. VLDL labeled with
[2-3H]glycerol and [1-14C]palmitate were infused into the rats, along with
[1-13C]palmitate bound to albumin and d-8-glycerol, and various metabolic
factors were assessed. The rates of appearance in plasma of fatty acids in
VLDL and albumin-bound free fatty acids (FFA) were about equal, on a molar
basis, and only a small fraction of the FFA flux was derived from VLDL. The
rate of direct oxidation of the fatty acids from VLDL was 4.4 +/- 0.9 mumol
of FA/kg X min, as compared with the value of 4.0 +/- 0.42 mumol of FA/kg X
min for plasma FFA. Four percent of the plasma glycerol flux was derived
from VLDL. Thus, the direct oxidation of fatty acids in VLDL played an
important role in the energy metabolism of the rats, accounting for a
percentage of the total CO2 production that was equal to the amount that
arose from the oxidation of plasma FFA. The oxidation of VLDL-fatty acids
did not involve prior entry of the fatty acids into the plasma FFA pool to
any significant extent.