title: Three calpain isoforms are autolyzed in rat fast-twitch muscle after eccentric contractions.
abstract: The present study investigated changes in autolysis of three calpain isoforms in skeletal muscles undergoing eccentric contractions (ECC), leading to prolonged force deficits. Rat extensor digitorum longus and tibialis anterior muscles were exposed to 200-repeated ECC in situ, excised immediately after or 3 or 6 days after cessation of ECC, and used for measures of force output and for biochemical analyses. Full restoration of tetanic force in ECC-treated muscles was not attained until 6 days of recovery. Maximal calpain activity determined by a fluorogenic substrate was unaltered immediately after ECC, but increased to 313 and 450 % after 3 and 6 days, respectively. Increases in the amount of autolyzed calpain-3 were apparent immediately and developed progressively with recovery time, whereas elevations of autolyzed μ- and m-calpain occurred after 3 and 6 days, respectively. The protein content was augmented only in m-calpain. It is suggested that the three calpain isoforms may be involved in the dismantling, repair, remodeling and/or regeneration processes in ECC-treated muscles.
authors.affiliation: Faculty of Food Culture, Kurashiki Sakuyo University, 3515 Nagao-Tamashima, Kurashiki-shi, Okayama, 710-0292, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Kanzaki
authors.forename: Mai
authors.initials: M
authors.lastname: Kuratani
authors.forename: Satoshi
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yanaka
authors.forename: Masanobu
authors.initials: M
authors.lastname: Wada
mesh_terms: D000818:Animals; D001329:Autolysis; D002154:Calpain / Q000378:metabolism*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000502:physiology*; D020033:Protein Isoforms; D051381:Rats; D017208:Rats, Wistar
chemical_list: D020033:Protein Isoforms; D002154:Calpain; C449000:m-calpain