TY - JOUR
T1 - Inorganic nitrate and nitrite supplementation fails to improve skeletal muscle mitochondrial efficiency in mice and humans
AU - Ntessalen, Maria
AU - Procter, Nathan Ek
AU - Schwarz, Konstantin
AU - Loudon, Brodie L
AU - Minnion, Magdalena
AU - Fernandez, Bernadette O
AU - Vassiliou, Vassilios S
AU - Vauzour, David
AU - Madhani, Melanie
AU - Constantin-Teodosiu, Dumitru
AU - Horowitz, John D
AU - Feelisch, Martin
AU - Dawson, Dana
AU - Crichton, Paul G
AU - Frenneaux, Michael P
N1 - Supported by Medical Research Council program grant MRC G1001340 (to M Madhani, M Feelisch, and MP Frenneaux).
We thank Lesley Cheyne for their contributions to the present study.
The authors’ responsibilities were as follows—VSV, M Madhani, JDH, MF, DD, MPF: designed the research; MN, NEKP, KS, BLL, M Minnion, BOF, DV, DC-T, PGC: conducted the research; DV: provided essential materials; MN, NEKP, M Minnion, BOF, DC-T, MF, PGC: analyzed the data; MN, NEKP, PGC, MPF: wrote the paper; MPF: had primary responsibility for the final manuscript; and all authors: read and approved the final manuscript. None of the authors reported a conflict of interest related to the study.
PY - 2020/1
Y1 - 2020/1
N2 - BACKGROUND: Inorganic nitrate, abundant in leafy green vegetables and beetroot, is thought to have protective health benefits. Adherence to a Mediterranean diet reduces the incidence and severity of coronary artery disease, whereas supplementation with nitrate can improve submaximal exercise performance. Once ingested, oral commensal bacteria may reduce nitrate to nitrite, which may subsequently be reduced to nitric oxide during conditions of hypoxia and in the presence of "nitrite reductases" such as heme- and molybdenum-containing enzymes.OBJECTIVE: We aimed to explore the putative effects of inorganic nitrate and nitrite on mitochondrial function in skeletal muscle.METHODS: Mice were subjected to a nitrate/nitrite-depleted diet for 2 wk, then supplemented with sodium nitrate, sodium nitrite, or sodium chloride (1 g/L) in drinking water ad libitum for 7 d before killing. Skeletal muscle mitochondrial function and expression of uncoupling protein (UCP) 3, ADP/ATP carrier protein (AAC) 1 and AAC2, and pyruvate dehydrogenase (PDH) were assessed by respirometry and Western blotting. Studies were also undertaken in human skeletal muscle biopsies from a cohort of coronary artery bypass graft patients treated with either sodium nitrite (30-min infusion of 10 μmol/min) or vehicle [0.9% (wt:vol) saline] 24 h before surgery.RESULTS: Neither sodium nitrate nor sodium nitrite supplementation altered mitochondrial coupling efficiency in murine skeletal muscle, and expression of UCP3, AAC1, or AAC2, and PDH phosphorylation status did not differ between the nitrite and saline groups. Similar results were observed in human samples.CONCLUSIONS: Sodium nitrite failed to improve mitochondrial metabolic efficiency, rendering this mechanism implausible for the purported exercise benefits of dietary nitrate supplementation. This trial was registered at clinicaltrials.gov as NCT04001283.
AB - BACKGROUND: Inorganic nitrate, abundant in leafy green vegetables and beetroot, is thought to have protective health benefits. Adherence to a Mediterranean diet reduces the incidence and severity of coronary artery disease, whereas supplementation with nitrate can improve submaximal exercise performance. Once ingested, oral commensal bacteria may reduce nitrate to nitrite, which may subsequently be reduced to nitric oxide during conditions of hypoxia and in the presence of "nitrite reductases" such as heme- and molybdenum-containing enzymes.OBJECTIVE: We aimed to explore the putative effects of inorganic nitrate and nitrite on mitochondrial function in skeletal muscle.METHODS: Mice were subjected to a nitrate/nitrite-depleted diet for 2 wk, then supplemented with sodium nitrate, sodium nitrite, or sodium chloride (1 g/L) in drinking water ad libitum for 7 d before killing. Skeletal muscle mitochondrial function and expression of uncoupling protein (UCP) 3, ADP/ATP carrier protein (AAC) 1 and AAC2, and pyruvate dehydrogenase (PDH) were assessed by respirometry and Western blotting. Studies were also undertaken in human skeletal muscle biopsies from a cohort of coronary artery bypass graft patients treated with either sodium nitrite (30-min infusion of 10 μmol/min) or vehicle [0.9% (wt:vol) saline] 24 h before surgery.RESULTS: Neither sodium nitrate nor sodium nitrite supplementation altered mitochondrial coupling efficiency in murine skeletal muscle, and expression of UCP3, AAC1, or AAC2, and PDH phosphorylation status did not differ between the nitrite and saline groups. Similar results were observed in human samples.CONCLUSIONS: Sodium nitrite failed to improve mitochondrial metabolic efficiency, rendering this mechanism implausible for the purported exercise benefits of dietary nitrate supplementation. This trial was registered at clinicaltrials.gov as NCT04001283.
KW - nitrate
KW - nitrite
KW - mitochondria
KW - uncoupling protein
KW - pyruvate dehydrogenase
KW - uncoupling proteins
UR - http://www.scopus.com/inward/record.url?scp=85077667635&partnerID=8YFLogxK
U2 - 10.1093/ajcn/nqz245
DO - 10.1093/ajcn/nqz245
M3 - Article
C2 - 31599928
VL - 111
SP - 79
EP - 89
JO - The American Journal of Clinical Nutrition
JF - The American Journal of Clinical Nutrition
SN - 0002-9165
IS - 1
ER -
