View source for Timpani 2016 Neurotherapeutics

{{Publication
|title=Timpani CA, Trewin AJ, Stojanovska V, Robinson A, Goodman CA, Nurgali K, Betik AC, Stepto N, Hayes A, McConell GK, Rybalka E (2016) Attempting to compensate for reduced neuronal nitric oxide synthase protein with nitrate supplementation cannot overcome metabolic dysfunction but rather has detrimental effects in Dystrophin-deficient ''mdx'' muscle. Neurotherapeutics [Epub ahead of print].
|info=[https://www.ncbi.nlm.nih.gov/pubmed/27921261 PMID: 27921261 Open Access]
|authors=Timpani CA, Trewin AJ, Stojanovska V, Robinson A, Goodman CA, Nurgali K, Betik AC, Stepto N, Hayes A, McConell GK, Rybalka E
|year=2016
|journal=Neurotherapeutics
|abstract=Duchenne muscular dystrophy arises from the loss of dystrophin and is characterized by calcium dysregulation, muscular atrophy, and metabolic dysfunction. The secondary reduction of neuronal nitric oxide synthase (nNOS) from the sarcolemma reduces NO production and bioavailability. As NO modulates glucose uptake, metabolism, and mitochondrial bioenergetics, we investigated whether an 8-week nitrate supplementation regimen could overcome metabolic dysfunction in the ''mdx'' mouse. Dystrophin-positive control (C57BL/10) and dystrophin-deficient ''mdx'' mice were supplemented with sodium nitrate (85 mg/l) in drinking water. Following the supplementation period, extensor digitorum longus and soleus were excised and radioactive glucose uptake was measured at rest (basal) and during contraction. Gastrocnemius was excised and mitochondrial respiration was measured using the OROBOROS Oxygraph. Tibialis anterior was analyzed immunohistochemically for the presence of dystrophin, nNOS, nitrotyrosine, IgG and CD45+ cells, and histologically to assess areas of damage and regeneration. Glucose uptake in the basal and contracting states was normal in unsupplemented ''mdx'' muscles but was reduced following nitrate supplementation in ''mdx'' muscles only. The mitochondrial utilization of substrates was also impaired in ''mdx'' gastrocnemius during phosphorylating and maximal uncoupled respiration, and nitrate could not improve respiration in ''mdx'' muscle. Although nitrate supplementation reduced mitochondrial hydrogen peroxide emission, it induced mitochondrial uncoupling in red gastrocnemius, increased muscle fiber peroxynitrite (nitrotyrosine), and promoted skeletal muscle damage. Our novel data suggest that despite lower nNOS protein expression and likely lower NO production in ''mdx'' muscle, enhancing NO production with nitrate supplementation in these mice has detrimental effects on skeletal muscle. This may have important relevance for those with DMD.
|keywords=Duchenne muscular dystrophy, Glucose uptake, Metabolism, Mitochondria, Nitrate supplementation
|mipnetlab=AU Melbourne Stepto NK
}}
{{Labeling
|area=Respiration, Pharmacology;toxicology
|diseases=Other
|organism=Mouse
|tissues=Skeletal muscle
|preparations=Permeabilized tissue
|couplingstates=LEAK, OXPHOS, ETS
|pathways=N, CIV, NS, Other combinations, ROX
|instruments=Oxygraph-2k, O2k-Fluorometer
|additional=[Epub ahead of print], Labels, 2017-01, Amplex UltraRed,
}}