Low expression of long-chain acyl-CoA dehydrogenase in human skeletal muscle

The first putative fatty acid transporter identified was plasma membrane fatty acid-binding protein (FABPpm). Later it was demonstrated that this protein is identical to the mitochondrial isoform of the enzyme aspartate aminotransferase. In recent years data from several cell types have emerged, indicating that FABPpm plays a role in the transport of long-chain saturated and unsaturated fatty acids. In the limited number of studies in human skeletal muscle it has been demonstrated that dietary composition and exercise training can influence the content of FABPpm. Ingestion of a fat-rich diet induces an increase in FABPpm protein content in human skeletal muscle in contrast to the decrease seen during consumption of a carbohydrate-rich diet. A similar effect of a fat-rich diet is also observed for cytosolic fatty acid-binding protein and fatty acid translocase/CD36 protein expression. Exercise training up regulates FABPpm protein content in skeletal muscle, but only in male subjects; no significant differences were observed in muscle FABPpm content in a cross-sectional study of female volunteers of varying training status, even though muscle FABPpm content did not depend on gender in the untrained state. A higher utilization of plasma long-chain fatty acids during exercise in males compared with females could explain the gender-dependent influence of exercise training on FABPpm. The mechanisms involved in the regulation of the function and expression of FABPpm protein remain to be clarified.

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Hormone-sensitive lipase activity and fatty acyl-CoA content in human skeletal muscle during prolonged exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.01181.2002 ◽

2003 ◽

Vol 95 (1) ◽

pp. 314-321 ◽

Cited By ~ 47

Author(s):

Matthew J. Watt ◽

George J. F. Heigenhauser ◽

Marcus O'Neill ◽

Lawrence L. Spriet

Keyword(s):

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Prolonged Exercise ◽

Dry Mass ◽

Fatty Acyl ◽

Hormone Sensitive Lipase ◽

Inhibitory Effects ◽

Hormone Sensitive ◽

Hydrolysis Of ◽

Long Chain

Hormone-sensitive lipase (HSL) catalyzes the hydrolysis of intramuscular triacylglycerols (IMTGs), but HSL regulation is poorly understood in skeletal muscle. The present study measured human skeletal muscle HSL activity at rest and during 120 min of cycling at 60% of peak O2 uptake. Several putative HSL regulators were also measured, including muscle long-chain fatty acyl-CoA (LCFA CoA) and free AMP contents and plasma epinephrine and insulin concentrations. HSL activity increased from resting levels by 10 min of exercise (from 2.09 ± 0.19 to 2.56 ± 0.22 mmol · min-1 · kg dry mass-1, P < 0.05), increased further by 60 min (to 3.12 ± 0.27 mmol · min-1 · kg dry mass-1, P < 0.05), and decreased to near-resting rates after 120 min of cycling. Skeletal muscle LCFA CoA increased ( P < 0.05) above rest by 60 min (from 15.9 ± 3.0 to 50.4 ± 7.9 μmol/kg dry mass) and increased further by 120 min. Estimated free AMP increased ( P < 0.05) from rest to 60 min and was ∼20-fold greater than that at rest by 120 min. Epinephrine was increased above rest ( P < 0.05) at 60 (1.47 ± 0.15 nM) and 120 min (4.87 ± 0.76 nM) of exercise. Insulin concentrations decreased rapidly and were lower than resting levels by 10 min and continued to decrease throughout exercise. In summary, HSL activity was increased from resting levels by 10 min, increased further by 60 min, and decreased to near-resting values by 120 min. The increased HSL activity at 60 min was associated with the stimulating effect of increased epinephrine and decreased insulin levels. After 120 min, the decreased HSL activity was associated with the proposed inhibitory effects of increased free AMP. The accumulation of LCFA CoA in the 2nd h of exercise may also have reduced the flux through HSL and accounted for the reduction in IMTG utilization previously observed late in prolonged exercise.

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Long-chain acyl-CoA synthetase 6 regulates lipid synthesis and mitochondrial oxidative capacity in human and rat skeletal muscle

The Journal of Physiology ◽

10.1113/jp272962 ◽

2016 ◽

Vol 595 (3) ◽

pp. 677-693 ◽

Cited By ~ 22

Author(s):

Bruno G. Teodoro ◽

Igor H. Sampaio ◽

Lucas H. M. Bomfim ◽

André L. Queiroz ◽

Leonardo R. Silveira ◽

...

Keyword(s):

Skeletal Muscle ◽

Lipid Synthesis ◽

Oxidative Capacity ◽

Rat Skeletal Muscle ◽

Mitochondrial Oxidative Capacity ◽

Chain Acyl ◽

Long Chain

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Regulation of plasma long-chain fatty acid oxidation in relation to uptake in human skeletal muscle during exercise

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00001.2004 ◽

2004 ◽

Vol 287 (4) ◽

pp. E696-E705 ◽

Cited By ~ 29

Author(s):

Carsten Roepstorff ◽

Bodil Vistisen ◽

Kirstine Roepstorff ◽

Bente Kiens

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Human Skeletal Muscle ◽

Fat Oxidation ◽

Lipid Binding ◽

Chain Fatty Acid ◽

Long Chain Fatty Acid ◽

Oxidation Rates ◽

Lcfa Uptake ◽

Long Chain

In the present study, we investigated possible sites of regulation of long-chain fatty acid (LCFA) oxidation in contracting human skeletal muscle. Leg plasma LCFA kinetics were determined in eight healthy men during bicycling (60 min, 65% peak oxygen uptake) with either high (H-FOX) or low (L-FOX) leg fat oxidation (H-FOX: 1,098 ± 140; L-FOX: 494 ± 84 μmol FA/min, P < 0.001), which was achieved by manipulating preexercise muscle glycogen (H-FOX: 197 ± 21; L-FOX: 504 ± 25 mmol/kg dry wt, P < 0.001). Several blood metabolites and hormones were kept nearly similar between trials by allocating a preexercise meal and infusing glucose intravenously during exercise. During exercise, leg plasma LCFA fractional extraction was identical between trials (H-FOX: 17.8 ± 1.6; L-FOX: 18.2 ± 1.8%, not significant), suggesting similar LCFA transport capacity in muscle. On the contrary, leg plasma LCFA oxidation was 99% higher in H-FOX than in L-FOX (421 ± 47 vs. 212 ± 37 μmol/min, P < 0.001). Probably due to the slightly higher ( P < 0.01) plasma LCFA concentration in H-FOX than in L-FOX, leg plasma LCFA uptake was nonsignificantly ( P = 0.17) higher (25%) in H-FOX than in L-FOX, yet the fraction of plasma LCFA uptake oxidized was 61% higher ( P < 0.05) in H-FOX than in L-FOX. Accordingly, the muscle content of several lipid-binding proteins did not differ significantly between trials, although fatty acid translocase/CD36 and caveolin-1 were elevated ( P < 0.05) by the high-intensity exercise and dietary manipulation allocated on the day before the experimental trial. The present data suggest that, in contracting human skeletal muscle with different fat oxidation rates achieved by manipulating preexercise glycogen content, transsarcolemmal transport is not limiting plasma LCFA oxidation. Rather, the latter seems to be limited by intracellular regulatory mechanisms.

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