Contributions of different fatty acid sources to very low-density lipoprotein-triacylglycerol in the fasted and fed states
BR Barrows, EJ Parks - The Journal of Clinical Endocrinology & …, 2006 - academic.oup.com
BR Barrows, EJ Parks
The Journal of Clinical Endocrinology & Metabolism, 2006•academic.oup.comContext: The liver's regulation of fatty acids (FAs) postprandially may contribute to risk of
metabolic diseases. Objective: Measurements of steady-state metabolism were used to
investigate sources of FAs used for very low-density lipoprotein (VLDL)-triacylglycerol (TG)
synthesis during fasting and feeding in vivo. Design/Intervention: Subjects were duodenally
fed a formula labeled with the stable isotope glyceryl tri-palmitate-d31 and iv infused with [1,
2, 3, 4-13C4]-palmitatic acid and [1-13C1]-acetate to quantitate the liver's use of FAs …
metabolic diseases. Objective: Measurements of steady-state metabolism were used to
investigate sources of FAs used for very low-density lipoprotein (VLDL)-triacylglycerol (TG)
synthesis during fasting and feeding in vivo. Design/Intervention: Subjects were duodenally
fed a formula labeled with the stable isotope glyceryl tri-palmitate-d31 and iv infused with [1,
2, 3, 4-13C4]-palmitatic acid and [1-13C1]-acetate to quantitate the liver's use of FAs …
Context: The liver’s regulation of fatty acids (FAs) postprandially may contribute to risk of metabolic diseases.
Objective: Measurements of steady-state metabolism were used to investigate sources of FAs used for very low-density lipoprotein (VLDL)-triacylglycerol (TG) synthesis during fasting and feeding in vivo.
Design/Intervention: Subjects were duodenally fed a formula labeled with the stable isotope glyceryl tri-palmitate-d31 and iv infused with [1,2,3,4-13C4]-palmitatic acid and [1-13C1]-acetate to quantitate the liver’s use of FAs originating from adipose tissue and de novo lipogenesis.
Setting/Participants: This study of healthy men (n = 12; body mass index, 24.4 ± 2.7 kg/m2) was conducted at a General Clinical Research Center.
Main Outcome Measures: Concentrations of metabolites during fasting and feeding, sources of FAs used for lipoprotein synthesis, rate of appearance of serum nonesterified FA (NEFA), and VLDL-TG were measured.
Results: During fasting, 77.2 ± 14.0% of VLDL-TG was derived from adipose FA recycling and 4.0 ± 3.6% from lipogenesis; with feeding, 43.6 ± 18.6% came from adipose FAs (P < 0.001), 8.2 ± 5.1% from lipogenesis (P < 0.001), 15.2 ± 13.7% from uptake of chylomicron-remnant TG, and 10.3 ± 6.9% from dietary FA spillover into the serum NEFA pool. Fed-state VLDL-TG from NEFA reesterification decreased in proportion to the reduction in adipose NEFA appearance.
Conclusion: These data: 1) quantify the extent to which the healthy liver manages its use of different sources of FAs that flow to it, 2) demonstrate how the postprandial reduction in adipose-NEFA flux may be partially replaced by other sources, and 3) highlight the potential for dietary FA spillover to support the continued dominance of NEFA as a substrate for VLDL-TG synthesis.
Oxford University Press