Nabben 2017 Am J Physiol Regul Integr Comp Physiol
|Nabben M, Schmitz JP, Ciapaite J, Le Clercq CM, van Riel NA, Haak HR, Nicolay K, de Coo IF, Smeets HJ, Praet SF, van Loon LJ, Prompers JJ (2017) Dietary nitrate does not reduce oxygen cost of exercise or improve muscle mitochondrial function in mitochondrial myopathy patients. Am J Physiol Regul Integr Comp Physiol 312:689-701.|
Abstract: Muscle weakness and exercise intolerance negatively affect the quality of life of mitochondrial myopathy patients. Short-term dietary nitrate supplementation has been shown to improve exercise performance and reduce oxygen cost of exercise in healthy humans and trained athletes. We investigated if 1 week of dietary inorganic nitrate supplementation decreases the oxygen cost of exercise and improves mitochondrial function in mitochondrial myopathy patients. Ten mitochondrial myopathy patients (40 ± 5 years, maximal whole-body oxygen uptake = 21.2 ± 3.2 mL/min/kg body weight, maximal workload = 122 ± 26 W) received 8.5 mg/kg body weight/day of inorganic nitrate (~7 mmol) for 8 days. Whole-body oxygen consumption at 50% of the maximal workload, in vivo skeletal muscle oxidative capacity (evaluated from post-exercise phosphocreatine recovery using 31P magnetic resonance spectroscopy) and ex vivo mitochondrial oxidative capacity in permeabilized skinned muscle fibers (measured with high-resolution respirometry) were determined before and after nitrate supplementation. Despite a 6-fold increase in plasma nitrate levels, nitrate supplementation did not affect whole-body oxygen cost during submaximal exercise. Additionally, no beneficial effects of nitrate were found on in vivo or ex vivo muscle mitochondrial oxidative capacity. This is the first time that the therapeutic potential of dietary nitrate for mitochondrial myopathy patients was evaluated. We conclude that 1 week of dietary nitrate supplementation does not reduce oxygen cost of exercise or improve mitochondrial function in the group of patients tested.
Copyright © 2016, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
• Keywords: 31P magnetic resonance spectroscopy, VO2 peak, Mitochondrial myopathy, Nitrate, Permeabilized muscle fibers • Bioblast editor: Kandolf G • O2k-Network Lab: NL Groningen Reijngoud RJ, NL Maastricht Schrauwen P, NL Eindhoven Nicolay K
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style Pathology: Myopathy
Organism: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Coupling state: LEAK, OXPHOS, ET Pathway: F, N, S HRR: Oxygraph-2k