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|Title: ||Effects of experimental pain in one and two jaw muscles on the functions of jaw motor system|
|Authors: ||Amhamed, Magda|
|Issue Date: ||22-Aug-2014|
|Publisher: ||University of Sydney|
Faculty of Dentistry
|Abstract: ||Stretch-induced muscle damage is a condition resulting in force decline in skeletal muscle after eccentric contractions. The exact mechanisms underlying this decline is unclear but has been attributed to EC-coupling failure. Both μ-calpain and junctophilin-1 are activated during eccentric contractions in single fibres and isolated muscle, however no studies have shown this in blood-perfused muscle. This study used an in vivo model to investigate the roles of μ-calpain and JP-1 in force decline of the tibialis anterior (TA) muscle of wild-type and mdx mice (model for Duchenne muscular dystrophy) during eccentric contractions. The hypothesis was that eccentric contractions would cause calcium influx through stretch-activated channels (SACs) thereby activating μ-calpain and JP-1, disrupting EC-coupling and thus force production. The TA was subjected to 20 eccentric contractions during supramaximal activation and removed after a 30 min recovery. Western blotting was used to detect protein activity. The results show force decline during eccentric contractions is associated with JP-1 proteolysis, but not μ-calpain autolysis. The SAC blocker, streptomycin, was effective in improving force during eccentric contractions but had no effect on JP-1 proteolysis in mdx mice, whilst a second SAC blocker, anti-TRPC-1, had no effect. The results suggest under more physiological conditions, JP-1 proteolysis is independent of calcium influx through SACs and is more likely due to mechanical damage or reactive oxygen species induced SR-calcium release.|
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|Rights and Permissions: ||The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.|
|Type of Work: ||PhD Doctorate|
|Type of Publication: ||Doctor of Philosophy Ph.D.|
|Appears in Collections:||Sydney Digital Theses (University of Sydney Access only)|
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|AMHAMED Magda - Final Thesis.pdf||Final Thesis||7.95 MB||Adobe PDF|
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