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Preconditioning contractions prevent the delayed onset of myofibrillar dysfunction after damaging eccentric contractions
Author(s) -
Yamada Ryotaro,
Himori Koichi,
Tatebayashi Daisuke,
Ashida Yuki,
Ikezaki Kazumi,
Miyata Hirohumi,
Kanzaki Keita,
Wada Masanobu,
Westerblad Håkan,
Yamada Takashi
Publication year - 2018
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jp276026
Subject(s) - eccentric , myofibril , medicine , cardiology , physics , quantum mechanics
Key points We examined the mechanisms underlying the positive effect of preconditioning contractions (PCs) on the recovery of muscle force after damaging eccentric contractions (ECCs). The mechanisms underlying the immediate force decrease after damaging ECCs differ from those causing depressed force with a few days’ delay, where reactive oxygen species (ROS) produced by invading immune cells play an important causative role. PCs counteracted the delayed onset force depression and this could be explained by prevention of immune cell invasion, which resulted in decreased myeloperoxidase‐mediated ROS production, hence avoiding cell membrane disruption, calpain activation and degenerative changes in myosin and actin molecules.Abstract Preconditioning contractions (PCs) have been shown to result in markedly improved contractile function during the recovery periods after muscle damage from eccentric contractions (ECCs). Here, we examined the mechanisms underlying the beneficial effect of PCs with a special focus on the myofibrillar function. Rat medial gastrocnemius muscles were exposed to 100 repeated damaging ECCs in situ and excised immediately (recovery 0, REC0) or after 4 days (REC4). PCs with 10 repeated non‐damaging ECCs were applied 2 days before the damaging ECCs. PCs improved in situ maximal isometric torque at REC4. Skinned muscle fibres were used to directly assess changes in myofibrillar function. PCs prevented the damaging ECC‐induced depression in maximum Ca 2+ ‐activated force at REC4. PCs also prevented the following damaging ECC‐induced effects at REC4: (i) the reduction in myosin heavy chain and actin content; (ii) calpain activation; (iii) changes in redox homeostasis manifested as increased expression levels of malondialdehyde‐protein adducts, NADPH oxidase 2, superoxide dismutase 2 and catalase, and activation of myeloperoxidase (MPO); (iv) infiltration of immune cells and loss of cell membrane integrity. Additionally, at REC0, PCs enhanced the expression levels of heat shock protein (HSP) 70, HSP25, and αB‐crystallin in the myofibrils and prevented the increased mRNA levels of granulocyte‐macrophage colony‐stimulating factor and interleukin‐6. In conclusion, PCs prevent the delayed force depression after damaging ECCs by an HSP‐dependent inhibition of degenerative changes in myosin and actin molecules caused by myeloperoxidase‐induced membrane lysis and subsequent calpain activation, which were triggered by an inflammatory reaction with immune cells invading damaged muscles.