The acute effects of differential dietary fatty acids on human skeletal muscle pyruvate dehydrogenase activity

Abstract

Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise, and its activity can be downregulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of the PDH complex (PDHa activity) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n = 7) underwent two fat-loading trials spaced at least 2 wk apart. Subjects consumed approximately 300 g saturated (SFA) or n-6 polyunsaturated fatty acid (PUFA) fat over the course of 5 h. Following this, participants cycled at 65% of their maximum oxygen uptake for 15 min. Muscle biopsies were taken before and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 +/- 0.07 to 0.54 +/- 0.19 mM over 5 h with SFA and from 0.11 +/- 0.04 to 0.35 +/- 0.13 mM with n-6 PUFA and were significantly lower throughout the n-6 PUFA trial. PDHa activity was unchanged following fat loading but increased at the onset of exercise in the SFA trial, from 1.18 +/- 0.27 to 2.16 +/- 0.37 mmol x min(-1) x kg wet wt(-1). This effect was negated in the n-6 PUFA trial (1.04 +/- 0.20 to 1.28 +/- 0.36 mmol x min(-1) x kg wet wt(-1)). PDH kinase was unchanged in both trials, suggesting that the attenuation of PDHa activity with n-6 PUFA was a result of changes in the concentrations of intramitochondrial effectors, potentially intramitochondrial NADH or Ca(2+). Our findings suggest that attenuated PDHa activity contributes to the preferential oxidation of n-6 PUFA during moderate-intensity exercise.

Cardiolipin content, linoleic acid composition, and tafazzin expression in response to skeletal muscle overload and unload stimuli

“…The HPTLC plate was viewed under ultraviolet light and the CL bands were marked and scraped into individual 15 ml kimex culture tubes and allowed to methylate in 2 ml of 6% H 2 SO 4 (w/v in methanol) overnight at 50 °C. Fatty acyl methyl esters were extracted with petroleum ether, dried down, reconstituted into dichloromethane (20 μl), and injected (2 μl) into a gas chromatograph (Trace GC Ultra, Thermo Electron, Milan, Italy) fitted with a split/splitless injector, a fast flame ionization detector, and Triplus AS autosampler (Trace GC Ultra, Thermo Electron) as previously described 45 . CL fatty acyl methyl esters were separated on an UFM RTX-WAX analytical column (Thermo Electron) using helium as a carrier gas.…”

Cardiolipin linoleic acid content and mitochondrial cytochrome c oxidase activity are associated in rat skeletal muscle

“…Total lipids from SS and IMF mitochondria (n = 6 per group) were extracted (Folch et al, 1957), and thin-layer chromatography (Mahadevappa and Holub, 1987) (Mahadevappa and Holub, 1987), and the fatty acid composition of each phospholipid was analyzed by gas chromatography (Bradley et al, 2008;Holloway et al, 2012;Stefanyk et al, 2010). A 0.1-1.0 ml sample of methyl esters from each sample was injected into a gas chromatograph (Trace GC Ultra, Thermo Electron, Milan, Italy) fitted with a split/splitless injector, a fast flame ionization detector, and Triplus AS autosampler (Trace GC Ultra, Thermo Electron).…”

Unsaturation of Mitochondrial Membrane Lipids is Related to Palmitate Oxidation in Subsarcolemmal and Intermyofibrillar Mitochondria

“…Briefly, isolated phospholipids were methylated (Mahadevappa and Holub 1987), and the fatty acid composition of each phospholipid was analyzed by gas chromatography (Bradley et al 2008;Stefanyk et al 2010). A 0.1-1.0 ll sample of methyl esters from each sample was injected into a gas chromatograph (Trace GC Ultra, Thermo Electron, Milan, SS subsarcolemmal mitochondria, IMF intermyofibrillar mitochondria, UI unsaturation index = P m i 9 n i , where m i is the mole percent and n i is the number of carbon-carbon double bonds of the fatty acid à Denotes significance from SS within the same tissue * and denote significance from heart and red muscle, respectively, within the same mitochondrial subpopulation G. P. Holloway et al: Mitochondrial Lipid Composition and Function 169 Italy) fitted with a split/splitless injector, a fast flame ionization detector, and Triplus AS autosampler (Trace GC Ultra, Thermo Electron).…”