Enhanced activity of eccentric contraction induces alterations in in vitro sarcoplasmic reticulum Ca2+ handling in rat hindlimb muscles
In order to investigate factors that contribute to eccentric contraction (ECC)-induced loss of tetanic force, Ca2+ uptake, Ca2+ release, and Ca2+-ATPase activity of the sarcoplasmic reticulum (SR) and sarcolemmal Na+-K+-ATPase activity were examined in rat fast-twitch skeletal muscles that underwent...
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| Main Authors: | , , , , , |
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| Format: | Book |
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Japanese Society of Physical Fitness and Sports Medicine,
2015-03-01T00:00:00Z.
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| Online Access: | Connect to this object online. |
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| Summary: | In order to investigate factors that contribute to eccentric contraction (ECC)-induced loss of tetanic force, Ca2+ uptake, Ca2+ release, and Ca2+-ATPase activity of the sarcoplasmic reticulum (SR) and sarcolemmal Na+-K+-ATPase activity were examined in rat fast-twitch skeletal muscles that underwent in situ ECC or isometric contraction (ISC) for up to 500 repetitions. The tetanic force at 60 Hz was more depressed in ECC-treated muscles than in ISC-treated muscles. SR Ca2+-ATPase activity displayed biphasic changes in response to ECC; after a temporary increase (up to 200 ECC repetitions), the activity decreased. With ECC, SR Ca2+ release rate and Na+-K+-ATPase activity decreased during the first 100 repetitions and remained almost constant thereafter. In contrast, the investigated variables (Ca2+-ATPase activity, Ca2+ release rate, and Na+-K+-ATPase activity) were unaltered in ISC-treated muscles. These results indicate that a more pronounced reduction in force output in ECC-treated muscles than in ISC-treated muscles might be attributable, at least in part, to impaired function of the SR Ca2+ release channel and/or Na+-K+-ATPase. |
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| Item Description: | 2186-8131 2186-8123 10.7600/jpfsm.4.117 |