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Effects of Dietary Selenium and Training on Mitochondrial Function in Young Horses
Author(s) -
White SH,
Warren LK,
Wohlgemuth S
Publication year - 2014
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12267_101
Subject(s) - respirometry , respiration , oxidative phosphorylation , cytochrome c oxidase , citrate synthase , zoology , medicine , endocrinology , horse , endurance training , chemistry , mitochondrion , biology , biochemistry , anatomy , enzyme , paleontology
Exercise training results in improved mitochondrial efficiency but it is unclear if dietary selenium level can further modify mitochondrial function. Methods A merican Q uarter H orse yearlings (n = 20; mean ± SE 18 ± 0.2 months) balanced with regard to age and sex were randomly assigned to four dietary S e and exercise training treatments for 14 weeks: 0.1 mg S e/kg DM with (n = 5) or without (n = 5) training or 0.3 mg S e/kg DM with (n = 5) or without (n = 5) training. Trained horses were exercised 4 d/wk for 30 min/d. At week 14, all horses underwent a 2 hr, 27.5 km submaximal exercise test ( SET ). Permeabilized muscle fibers obtained from the gluteus medius of horses at rest were analysed for mitochondrial function via high resolution respirometry. Mitochondrial oxidative phosphorylation capacity with Complex I substrates was determined using the respiratory control ratio ( RCR ) of state 3 (with ADP ) and state 2 (without ADP ; leak respiration). Electron transport system capacity ( ETSC ) was determined by uncoupling phosphorylation and respiration using carbonyl cyanide p‐trifluoromethoxyphenylhydrazone. Cytochrome c oxidase ( CCO ) and citrate synthase ( CS ) activities were assessed in resting muscle samples obtained at week 0 and 14, and in response to the SET . Data were analysed using a mixed model ANOVA . Results Leak, state 3, ETSC , CS and CCO were higher (P<0.05) at wk 14 compared to wk 0 in all horses, but were not affected by training or S e level. Additionally, CS and CCO were unaffected by the SET . Conclusions Mitochondrial number ( CS activity) and efficiency were unaffected by training and dietary S e level, but did increase over time, perhaps due to growth of horses. A more strenuous training protocol may be needed to induce mitochondrial adaptations. Ethical Animal Research This project was approved by the Institute of Food and Agricultural Sciences Animal Care Committee at the U niversity of F lorida (approval number 016‐12ANS). Sources of funding: Partial financial support of this project was provided by A lltech, N icholasville, KY , USA . Competing interests: none.