41. Free radicals 2 Flashcards
What was the summary surrounding free radicals and skeletal muscle?
Oxidative stress is needed for muscle development
Repeated contractions alters the skeletal physiological environemnt
Oxidation seems to be important for maintaing structure, function and for adaptation
What drives oxygen species within skeletal muscle
Increased oxygen consumption lowers oxygen tension during exercise which increases oxygen species
So too does increase in temperature and decrease in pH
Provide the main examples of the oxygen species within skeletal muscle
Xanthine oxidase
PLA2 dependent processes
Hydrogen peroxide
NADPH oxidase
Discuss how NADPH oxidase contribute to reactive oxygen species
Generates superoxide by transferring electrons to molecular oxygen in the sacroplasmic reticulum and t tubules.
How does superoxide affect the skeletal muscle?
Affects calcium release by oxidation of the ryanodine receptor
Phospholipase A2 can also contribute to oxidation. How does it do this?
Creates arachodonic acid which is a substrate for generating enzyme systems for oxygen species
It also activates NADPH which stimulate reactive oxygen species
How does Xanthine oxidase increase reactive oxygen species?
Produces superoxide via hypoxanthine to xanthine
Unsure of contribution due to lower levels in humans comapred to rat levels
What can be said about oxidation with relation to oxygen force
Free radical production is required to achieve maximal force production
However if the dose is too high we see a reduction in force production
How does oxidation increase muscle force?
Increase the opening of the sarcoplasmic reticulums calcium storage
It is also hypothesised that it increases calcium sensitivity
Changes to myosin and troponin C also occur
How can antioxidants help with reductive stress?
Found to reduce muscle fatigue in submaximal contraction
