AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 2 263-G269, Copyright © 1986 by American Physiological Society
Steady-state kinetic analysis of triacylglycerol delivery into mesenteric lymph
C. M. Mansbach 2nd and A. Arnold
The output of triacylglycerol in chylomicrons can be increased 60% by
prefeeding rats with a 20% fat diet or 110% by including
phosphatidylcholine in a lipid infusion. The present study was designed to
determine whether the increment was due to an expansion of the chylomicron
triacylglycerol precursor pool or an increase in its fractional turnover
rate. A steady-state kinetic model was established in rats receiving 135
mumol glyceryl trioleate/h. The decay in specific activity of
triacylglycerol after removal of radiolabeled glyceryl trioleate from the
duodenal infusate was followed for 4 h and analyzed by the SAAM 23 program.
It was found that the fractional turnover rate of the chylomicron precursor
pool remained the same in each experimental condition. However, the pool
was found to expand in direct proportion to the chylomicron triacylglycerol
output. Functionally the infused [3H]glyceride-glycerol and tri[14C]oleate
behaved the same in lymph chylomicrons and was 90% of infusate specific
activity. In summary, these data suggest that increases in chylomicron
triacylglycerol output are dependent on the size of the mucosal precursor
pool and the monoacylglycerol acyltransferase synthetic pathway for its
triacylglycerol.
