TITLE:
Effect of Dietary Nitrate on Force Production and Sarcoplasmic Reticulum Ca2+ Handling in Rat Fast-Twitch Muscles Following Eccentric Contraction
AUTHORS:
Satoshi Matsunaga, Chihiro Aibara, Daiki Watanabe, Keita Kanzaki, Yurie Morizaki, Sumiko Matsunaga-Futatsuki, Masanobu Wada
KEYWORDS:
Supplementation, Ca2+-ATPase Activity, Ca2+ Uptake, Ca2+ Release
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.8 No.12,
December
27,
2018
ABSTRACT: 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.