Author(s)

Satoshi Matsunaga^1*, Chihiro Aibara², Daiki Watanabe³, Keita Kanzaki⁴, Yurie Morizaki¹, Sumiko Matsunaga-Futatsuki⁵, Masanobu Wada²

¹Faculty of Education, University of Miyazaki, Miyazaki, Japan.
²Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Japan.
³Department of Engineering Science, University of Electro-Communications, Chofu, Japan.
⁴Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Kurashiki, Japan.
⁵Department of Communication and Liberal Arts, Minami Kyushu Junior College, Miyazaki, Japan.

Impaired excitation-contraction coupling occurs in eccentric contraction (ECC)-induced damaged muscles. It has been suggested that sarcoplasmic reticulum (SR) is susceptible to damage in the overstretched regions possibly marking the basis of excitation-contraction coupling damage. Recent studies have shown that dietary nitrate supplementation enhances SR function in fast-twitch muscles. In this study, we aimed to investigate whether dietary nitrate supplementation can alleviate a decline in muscle contractile properties and SR function following ECC. To this end, force production, Ca²⁺ uptake, Ca²⁺ release, and Ca²⁺-ATPase activity of the SR were examined in rat fast-twitch muscles immediately following ECC for 200 repetitions. In comparison with contralateral resting muscles, nitrate supplementation for up to 3 days resulted in an obvious decline in force production. However, there were no differences in terms of force production between 6-day nitrate-treated and contralateral muscles. Similar to the observations regarding force production, the SR Ca²⁺ release rate changed from an obvious decrease following the 0- and 3-day dietary nitrate supplementation to no difference following the 6-day nitrate supplementation. In contrast, ECC decreased the Ca²⁺-ATPase activity and Ca²⁺ uptake rate, irrespective of the period of dietary nitrate supplementation. Overall, these results indicate that dietary nitrate supplementation can alleviate ECC-related decreases in force production mediated through inhibited reductions in the SR Ca²⁺ release function.

Supplementation, Ca²⁺-ATPase Activity, Ca²⁺ Uptake, Ca²⁺ Release

Matsunaga, S. , Aibara, C. , Watanabe, D. , Kanzaki, K. , Morizaki, Y. , Matsunaga-Futatsuki, S. and Wada, M. (2018) Effect of Dietary Nitrate on Force Production and Sarcoplasmic Reticulum Ca²⁺ Handling in Rat Fast-Twitch Muscles Following Eccentric Contraction. Open Journal of Applied Sciences, 8, 607-618. doi: 10.4236/ojapps.2018.812049.