The effects of eccentric contraction on myofibrillar proteins in rat skeletal muscle

Abstract

The present study investigated the effects of eccentric muscle contractions (ECC) on the content of myofibrillar proteins (my-proteins) and the catalytic activity of myofibrillar ATPase (my-ATPase) in skeletal muscles. Rat extensor digitorum longus and tibialis anterior muscles were exposed to 200-repeated ECC or isometric contractions (ISC) and used for measures of force output and for biochemical analyses, respectively. Whereas in ISC-treated muscles, full restoration of tetanic force was attained after 2 days of recovery, force developed by ECC-treated muscles remained depressed (P < 0.05) after 6 days. The total my-protein content and the relative content of myosin heavy chain (MHC) in total my-proteins were unaltered during 4 days of recovery after ECC, but fell (P < 0.05) to 55.9 and 63.4% after 6 days of recovery, respectively. my-ATPase activity expressed on a my-protein weight basis was unaltered immediately after ECC. However, it decreased (P < 0.05) to 75.3, 45.3, and 49.3% after 2, 4 and 6 days of recovery, respectively. Total maximal calpain activity measured at 5 mM Ca(2+) was significantly augmented (P < 0.05) after 2 days of recovery, reaching a level of threefold higher after 6 days. These alterations were specific for ECC and not observed for ISC. These results suggest that depressions in my-ATPase activity contribute to ECC-induced decreases in force and power which can take a number of days to recover.

The Efficacy of Microcurrent Therapy on Eccentric Contraction-Induced Muscle Damage in Rat Fast-Twitch Skeletal Muscle

“…As reported many times previously, features common to ECC are that this type of muscle contraction results in greater depressions in force, compared to concentric and isometric contractions and that restoration of force is a very slow process, in some instance requiring several days or more for full recovery [22] [25]. The present investigation, for the first time, provides evidence that MC treatment can facilitate restoration of force production after ECC.…”

Enhanced activity of eccentric contraction induces alterations in <i>in vitro</i> sarcoplasmic reticulum Ca²⁺ handling in rat hindlimb muscles

“…Therefore, EDL and TA muscles were used to measure force output and biochemical analyses, respectively. As discussed by Kanzaki et al 20) , EDL and TA muscles have nearly the same composition of fast-twitch fibers, and exhibit similar functional deficits after ECC. Some previous studies assumed that these two muscles are similarly affected by ECC 20,22) .…”

“…As discussed by Kanzaki et al 20) , EDL and TA muscles have nearly the same composition of fast-twitch fibers, and exhibit similar functional deficits after ECC. Some previous studies assumed that these two muscles are similarly affected by ECC 20,22) . At the end of the experiment, the rats were killed by brief diethyl ether inhalation followed by intraperitoneal anesthetic overdose (pentobarbital sodium, 10 mg 100 g -1 body weight).…”

“…ECC was induced by the methods that were described by Kanzaki et al 9,20) . Briefly, the animal was placed in the supine position on the supporting platform and the left foot was secured in a foot holder that was attached to the rim of the servomotor.…”

“…Isometric contractile force of the EDL muscles was recorded at 30°C in a chamber that was filled with a solution of the following composition (in mM): 115 NaCl, 5 KHCO3, 1 MgCl2, 20 NaHCO3, 2 CaCl2, 5 N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, 11 glucose, 0.3 glutamic acid, and 0.38 glutamine, as previously described 9,20) . The solution was continuously bubbled with 95% O2 -5% CO2, which yielded a pH of 7.4.…”