Repository logo

Nitrate enhances skeletal muscle fatty acid oxidation via a nitric oxide-cGMP-PPAR-mediated mechanism



Change log


Ashmore, Tom 
Roberts, Lee D 
Morash, Andrea J 
Kotwica, Aleksandra O 
Finnerty, John 


BACKGROUND. Insulin sensitivity in skeletal muscle is associated with metabolic flexibility, including a high capacity to increase fatty acid (FA) oxidation in response to increased lipid supply. Lipid overload, however, can result in incomplete FA oxidation and accumulation of potentially harmful intermediates where mitochondrial TCA cycle capacity cannot keep pace with rates of β-oxidation. Enhancement of muscle FA oxidation in combination with mitochondrial biogenesis is therefore emerging as a strategy to treat metabolic disease. Dietary inorganic nitrate was recently shown to reverse aspects of the metabolic syndrome in rodents by as yet incompletely-defined mechanisms.

RESULTS. Here we report that nitrate enhances skeletal muscle FA oxidation in rodents in a dose- dependent manner. We show that nitrate induces FA oxidation through a soluble-guanylate cyclase (sGC)/cGMP-mediated PPARβ/δ and PPARα-dependent mechanism. Enhanced PPARβ/δ and PPARα expression and DNA-binding induces expression of FA oxidation enzymes, increasing muscle carnitine and lowering tissue malonyl-CoA concentrations, thereby supporting intra-mitochondrial pathways of FA oxidation and enhancing mitochondrial respiration. At higher doses, nitrate induces mitochondrial biogenesis, further increasing FA oxidation and lowering long-chain FA concentrations. Meanwhile, nitrate did not affect mitochondrial FA oxidation in PPARα -/- mice. In C2C12 myotubes, nitrate increased expression of the PPARα targets Cpt1b, Acadl, Hadh and Ucp3, and enhanced oxidative phosphorylation rates with palmitoyl-carnitine, however these changes in gene expression and respiration were prevented by inhibition of either sGC or protein kinase G (PKG). Elevation of cGMP via the inhibition of phosphodiesterase 5 (PDE5) by sildenafil, also increased expression of Cpt1b, Acadl and Ucp3 as well as CPT1B protein levels, and further enhanced the effect of nitrate supplementation.

CONCLUSIONS. Nitrate may therefore be effective in the treatment of metabolic disease by inducing FA oxidation in muscle.



Muscle, metabolism, mitochondria, fatty acid oxidation, nitrate, nitric oxide

Journal Title

BMC Biology

Conference Name

Journal ISSN


Volume Title



BioMed Central
BBSRC (BB/H013539/2)
Wellcome Trust (092738/Z/10/Z)
This work was kindly supported by a British Heart Foundation studentship to TA (FS/09/050). AJMu thanks the Research Councils UK for supporting his academic fellowship. LDR is supported by the Medical Research Council-Human Nutrition Research Elsie Widdowson Fellowship. AJMo thanks the Natural Sciences and Engineering Research Council for supporting her postdoctoral fellowship. MF acknowledges support from the Medical Research Council (G1001536). JLG thanks the Medical Research Council (MC_UP_A090_1006), the Biotechnology and Biological Sciences Research Council (BB/H013539/2) and British Heart Foundation for supporting work in his laboratory.