Abstract
A pulse ([14C]palmitate)-chase ([3H]palmitate) approach was used to study intramuscular triglyceride (imTG) fatty acid and plasma free fatty acid (FFA) kinetics during exercise at ~45% peak O2 consumption in 12 adults. Vastus lateralis muscle was biopsied before and after 90 min of bicycle exercise; 3H2O production, breath 14CO2 excretion and lipid oxidation (indirect calorimetry) rates were measured during exercise. Results: during exercise, 8.2 ± 1.2 and 8.4 ± 0.7 μmol·kg-1·min-1 of imTG fatty acids and plasma FFA, respectively, were oxidized according to isotopic measurements. The sum of these two values was not different (P =0.6) from lipid oxidation by indirect calorimetry (15.4 ± 1.6 μmol·kg-1·min-1); the isotopic and indirect calorimetry values were correlated (r = 0.79, P < 0.005). During exercise, imTG turnover rate was 0.32 ± 0.07%/min (6.0 ± 2.0 μmol of imTG·kg wet muscle-1·min-1) and plasma FFA were incorporated into imTG at a rate of 0.7 ± 0.1 μmol·kg wet muscle-1·min-1. The imTG pool size did not change during exercise. This pulse-chase, dual tracer appears to be a reasonable approach to measure oxidation and synthesis kinetics of imTG.
Original language | English (US) |
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Pages (from-to) | 2057-2064 |
Number of pages | 8 |
Journal | Journal of applied physiology |
Volume | 89 |
Issue number | 5 |
DOIs | |
State | Published - 2000 |
Keywords
- Body composition
- Free fatty acids
- [C]palmitate
ASJC Scopus subject areas
- Physiology
- Physiology (medical)