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Contribution of intramuscular TG and plasma FFA to the long chain acyl‐carnitine pool: effects of insulin in trained and untrained humans
Author(s) -
Kanaley Jill,
Sheehan Michael,
Guo ZengKui,
Jensen Michael D
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.958.1
Subject(s) - medicine , endocrinology , basal (medicine) , lipolysis , chemistry , glucose clamp technique , insulin , insulin resistance , pancreatic hormone , biology , adipose tissue
This study examined the plasma FFA, intramuscular long chain acylcarnitine (LCAC) fatty acids and imTG stores during basal and hyperinsulinemic conditions. Methods: Endurance trained (TR, n=8) and sedentary individuals (SED, n=15) were studied under overnight postabsorptive and euglycemic hyperinsulinemic clamp (1.0mU·kg FFM −1 ·min −1 ) conditions. FFA kinetics were measured using a 5‐h infusion of [U‐ 13 C]oleate, for labeling of imTG and LCAC pools. Muscle biopsies were performed to measure imTG and imLCAC enrichment at 1400 h after 5‐h of infusion. imTG concentrations were greater in TR than SED individuals (P<0.01). TableSED TrainedSaline** Clamp Saline** Clampplasma oleate FFA (mpe) 0.210±0.018* 0.271±0.036* 0.189±0.026* 0.361±0.050* imLCAC (mpe) 0.025±0.003 0.005±0.002 0.016±0.005 0.002±0.002 imTG (mpe) 0.018±0.003† 0.011±0.001† 0.024±0.004† 0.013±0.001†** P<0.001 saline vs. clamp; *P<0.000 between compartment (plasma vs. imLCAC vs. imTG); †P<0.000 imLCAC and imTGMethods: Endurance trained (TR, n=8) and sedentary individuals (SED, n=15) were studied under overnight postabsorptive and euglycemic hyperinsulinemic clamp (1.0mU·kg FFM −1 ·min −1 ) conditions. FFA kinetics were measured using a 5‐h infusion of [U‐ 13 C]oleate, for labeling of imTG and LCAC pools. Muscle biopsies were performed to measure imTG and imLCAC enrichment at 1400 h after 5‐h of infusion. Conclusion: The imTG contributes more to the imLCAC pools than plasma FFA both in the basal and hyperinsulinemic state, and hyperinsulinemia suppressed oleate FFA entry into the imLCAC pools, more so in trained than untrained adults. Muscle fatty acid oxidation is largely via obligatory cycling of fatty acids through imTG or other intracellular complex lipid pools.