Role of human liver in ffa reesterification and of lipogenesis and
reesterification in triglycerides secretion.
Diraison, Frederique, and Michel Beylot.
Laboratoire de Physiopathologie M[acute]etabolique et R[acute]enale
and the Centre de Recherche en Nutrition Humaine de Lyon, 69008 Lyon,
France
APStracts 4:0244E, 1997.
In order to measure 1) the contribution of hepatic de novo lipogenesis
(DNL) and plasma free fatty acid (FFA) reesterification to plasma
triglycerides (TG) secretion, 2) the role of oxidation, hepatic and
extra-hepatic reesterification in FFA utilization, five normal
subjects drank deuterated water and were infused (post-absorptive
state) with [1-13C]palmitate and [1,2,3-2H5]glycerol. Total lipid
oxidation (Lox) was measured by indirect calorimetry. FFA oxidation
(2.76+0.65 [mu]mol.kg-1.min-1) accounted for 45% of FFA turnover rate
(Rt) (6.04+1.04 [mu]mol.kg-1.min-1) and 91% of Lox; FFA
reesterification was 3.27+ 0.54 [mu]mol.kg-1.min-1 . Fractional and
absolute TG Rt were 0.21+0.02 h-1 and 0.11+0.05[mu]mol.kg-1.min-1.
DNL accounted for 3.9+0.9 % of TG secretion and hepatic FFA
reesterification for 49.4+5.7%; this last process represented an
utilization of FFA of 0.16+0.02 [mu]mol.kg-1.min-1. Conclusion : in
the post-absorptive state 1) DNL and FFA reesterification account
only for 50-55% of TG secretion, the remaining being provided
presumably by stored lipids or lipoproteins taken up by liver, 2)
most reesterification occurs in extra-hepatic tissues, 3) oxidation
and reesterification contribute each about one half to FFA
utilization; FFA oxidation accounts for almost all Lox.
Received 2 June 1997; accepted in final form 28 October 1997.
APS Manuscript Number E259-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 14 November 1997