Contribution of very low-density lipoprotein triglyceride fatty acids to postabsorptive free fatty acid flux in obese humans

Nikki C. Bush, Jessica M. Triay, Nicola W. Gathaiya, Kazanna C. Hames, Michael Dennis Jensen

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Objective In the fasting state, plasma free fatty acids (FFA) are thought to derive almost exclusively from adipose tissue lipolysis. However, there are mixed reports as to whether the spillover of fatty acids (FA) from very low-density lipoprotein triglyceride (VLDL-TG) hydrolysis contributes significantly to the plasma FFA pool. Because substantial VLDL-TG fatty acid spillover into the plasma FFA pool would profoundly impact the interpretation of isotope dilution measures of FFA flux, we investigated the contribution of VLDL-TG spillover to plasma FFA appearance. Materials/Methods Eighteen obese adults (15 women) participated in these studies. Each volunteer received a primed, continuous infusion of their own ex-vivo labeled ([1- 14C]triolein) VLDL-TG and a continuous infusion of [U- 13C]oleate (8 nmol·kg fat free mass- 1· min- 1) to measure VLDL-TG and FFA rate of appearance (Ra), respectively. The presence of 14C-oleate in the plasma FFA-oleate pool was used to calculate the contribution of spillover from VLDL-TG-oleate to the plasma FFA-oleate Ra. Results The spillover rate of VLDL-TG-oleate into plasma FFA-oleate was 6 ± 2 μmol/min (7% ± 2% of [ 14C]oleate from VLDL-TG) and FFA-oleate flux was 240 ± 61 μmol/min. Thus, only 3% ± 1% of total plasma FFA-oleate appearance could be accounted for by VLDL-TG spillover. Conclusion The contribution of VLDL-TG spillover to the total plasma FFA pool is negligible and will not materially affect the interpretation of FFA flux measures as an index of adipose tissue lipolysis.

Original languageEnglish (US)
Pages (from-to)137-140
Number of pages4
JournalMetabolism: Clinical and Experimental
Volume63
Issue number1
DOIs
StatePublished - Jan 2014

Fingerprint

Nonesterified Fatty Acids
Oleic Acid
Fatty Acids
Lipolysis
very low density lipoprotein triglyceride
Adipose Tissue
Triolein
Lipoprotein(a)
Isotopes
Volunteers
Fasting
Hydrolysis
Fats

Keywords

  • [C]triolein
  • [U-C]oleate
  • Hypertriglyceridemia
  • Isotope dilution

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Contribution of very low-density lipoprotein triglyceride fatty acids to postabsorptive free fatty acid flux in obese humans. / Bush, Nikki C.; Triay, Jessica M.; Gathaiya, Nicola W.; Hames, Kazanna C.; Jensen, Michael Dennis.

In: Metabolism: Clinical and Experimental, Vol. 63, No. 1, 01.2014, p. 137-140.

Research output: Contribution to journalArticle

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abstract = "Objective In the fasting state, plasma free fatty acids (FFA) are thought to derive almost exclusively from adipose tissue lipolysis. However, there are mixed reports as to whether the spillover of fatty acids (FA) from very low-density lipoprotein triglyceride (VLDL-TG) hydrolysis contributes significantly to the plasma FFA pool. Because substantial VLDL-TG fatty acid spillover into the plasma FFA pool would profoundly impact the interpretation of isotope dilution measures of FFA flux, we investigated the contribution of VLDL-TG spillover to plasma FFA appearance. Materials/Methods Eighteen obese adults (15 women) participated in these studies. Each volunteer received a primed, continuous infusion of their own ex-vivo labeled ([1- 14C]triolein) VLDL-TG and a continuous infusion of [U- 13C]oleate (8 nmol·kg fat free mass- 1· min- 1) to measure VLDL-TG and FFA rate of appearance (Ra), respectively. The presence of 14C-oleate in the plasma FFA-oleate pool was used to calculate the contribution of spillover from VLDL-TG-oleate to the plasma FFA-oleate Ra. Results The spillover rate of VLDL-TG-oleate into plasma FFA-oleate was 6 ± 2 μmol/min (7{\%} ± 2{\%} of [ 14C]oleate from VLDL-TG) and FFA-oleate flux was 240 ± 61 μmol/min. Thus, only 3{\%} ± 1{\%} of total plasma FFA-oleate appearance could be accounted for by VLDL-TG spillover. Conclusion The contribution of VLDL-TG spillover to the total plasma FFA pool is negligible and will not materially affect the interpretation of FFA flux measures as an index of adipose tissue lipolysis.",
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AU - Triay, Jessica M.

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AU - Hames, Kazanna C.

AU - Jensen, Michael Dennis

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N2 - Objective In the fasting state, plasma free fatty acids (FFA) are thought to derive almost exclusively from adipose tissue lipolysis. However, there are mixed reports as to whether the spillover of fatty acids (FA) from very low-density lipoprotein triglyceride (VLDL-TG) hydrolysis contributes significantly to the plasma FFA pool. Because substantial VLDL-TG fatty acid spillover into the plasma FFA pool would profoundly impact the interpretation of isotope dilution measures of FFA flux, we investigated the contribution of VLDL-TG spillover to plasma FFA appearance. Materials/Methods Eighteen obese adults (15 women) participated in these studies. Each volunteer received a primed, continuous infusion of their own ex-vivo labeled ([1- 14C]triolein) VLDL-TG and a continuous infusion of [U- 13C]oleate (8 nmol·kg fat free mass- 1· min- 1) to measure VLDL-TG and FFA rate of appearance (Ra), respectively. The presence of 14C-oleate in the plasma FFA-oleate pool was used to calculate the contribution of spillover from VLDL-TG-oleate to the plasma FFA-oleate Ra. Results The spillover rate of VLDL-TG-oleate into plasma FFA-oleate was 6 ± 2 μmol/min (7% ± 2% of [ 14C]oleate from VLDL-TG) and FFA-oleate flux was 240 ± 61 μmol/min. Thus, only 3% ± 1% of total plasma FFA-oleate appearance could be accounted for by VLDL-TG spillover. Conclusion The contribution of VLDL-TG spillover to the total plasma FFA pool is negligible and will not materially affect the interpretation of FFA flux measures as an index of adipose tissue lipolysis.

AB - Objective In the fasting state, plasma free fatty acids (FFA) are thought to derive almost exclusively from adipose tissue lipolysis. However, there are mixed reports as to whether the spillover of fatty acids (FA) from very low-density lipoprotein triglyceride (VLDL-TG) hydrolysis contributes significantly to the plasma FFA pool. Because substantial VLDL-TG fatty acid spillover into the plasma FFA pool would profoundly impact the interpretation of isotope dilution measures of FFA flux, we investigated the contribution of VLDL-TG spillover to plasma FFA appearance. Materials/Methods Eighteen obese adults (15 women) participated in these studies. Each volunteer received a primed, continuous infusion of their own ex-vivo labeled ([1- 14C]triolein) VLDL-TG and a continuous infusion of [U- 13C]oleate (8 nmol·kg fat free mass- 1· min- 1) to measure VLDL-TG and FFA rate of appearance (Ra), respectively. The presence of 14C-oleate in the plasma FFA-oleate pool was used to calculate the contribution of spillover from VLDL-TG-oleate to the plasma FFA-oleate Ra. Results The spillover rate of VLDL-TG-oleate into plasma FFA-oleate was 6 ± 2 μmol/min (7% ± 2% of [ 14C]oleate from VLDL-TG) and FFA-oleate flux was 240 ± 61 μmol/min. Thus, only 3% ± 1% of total plasma FFA-oleate appearance could be accounted for by VLDL-TG spillover. Conclusion The contribution of VLDL-TG spillover to the total plasma FFA pool is negligible and will not materially affect the interpretation of FFA flux measures as an index of adipose tissue lipolysis.

KW - [C]triolein

KW - [U-C]oleate

KW - Hypertriglyceridemia

KW - Isotope dilution

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