AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 3 386-R395, Copyright © 1983 by American Physiological Society
Nascent and remnant lipoprotein turnover in rats: experimental design and simulation
N. Baker, H. J. Rostami and J. Elovson
We have attempted to predict the kinetic behavior of the complex very
low-density lipoprotein (VLDL; d less than 1.006) fraction in blood plasma
of rats in the steady state. Specifically we proposed a simple model with
two different kinds of nascent VLDL particles derived from the liver, one
containing apoprotein B (PI/II) [apoB(PI/II)], the high-molecular-weight
apoB, and the other, apoprotein B (PIII) [apoB(PIII)], the
low-molecular-weight apoB. Two other particles, the corresponding remnants
derived from the nascent VLDL particles were also included. Then a number
of feasible in vivo tracer experiments were considered in which VLDL
labeled in the apoB and/or triglyceride (TG) moieties would be injected
into recipient rats and the kinetic behavior of the various compartments
predicted by simulation analysis. In addition the kinetic behavior of
products such as free fatty acids formed during hydrolysis of labeled TG
fatty acids and liver TG derived from labeled circulating remnants was
considered. Both the relative sizes of nascent and remnant particles and
the extent of average hydrolysis of nascent VLDL-TG (before formation of a
remnant particle) were considered in our analysis. On the basis of these
predictions we have suggested a number of experimental approaches that
should be helpful in defining the relative pool sizes and the turnover
rates of each kind of particle in vivo.
