Systemic free fatty acid disposal into very low-Density lipoprotein triglycerides

Christina Koutsari, Manpreet S. Mundi, Asem H. Ali, Bruce W. Patterson, Michael D. Jensen

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

We measured the incorporation of systemic free fatty acids (FFA) into circulating very low-density lipoprotein triglycerides (VLDLTGs) under postabsorptive, postprandial, and walking conditions in humans. Fifty-five men and 85 premenopausal women with BMI 18-24 (lean) and 27-36 kg/m2 (overweight/obese) received an intravenous bolus injection of [1,1,2,3,3- 2H5]glycerol (to measure VLDL-TG kinetics) and either [1-14C]palmitate or [9,10-3H] palmitate to determine the proportion of systemic FFA that is converted to VLDL-TG. Experiments started at 0630 h after a 12-h overnight fast. In the postabsorptive protocol, participants rested and remained fasted until 1330 h. In the postprandial protocol, volunteers ingested frequent portions of a fat-free smoothie. In the walking protocol, participants walked on a treadmillfor 5.5 h at ̃ 33 resting energy expenditure. Approximately 7% of circulating FFA was converted into VLDL-TG. VLDL-TG secretion rates (SRs) were not statistically different among protocols. Visceral fat mass was the only independent predictor of VLDL-TG secretion, explaining 33-57% of the variance. The small proportion of systemic FFA that is converted to VLDL-TG can confound the expected relationship between plasma FFA concentration and VLDL-TG SRs. Regulation of VLDL-TG secretion is complex in that, despite a broad spectrum of physiological FFA concentrations, VLDL-TG SRs did not vary based on different acute substrate availability.

Original languageEnglish
Pages (from-to)2386-2395
Number of pages10
JournalDiabetes
Volume62
Issue number7
DOIs
StatePublished - Jul 1 2013

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