Flashcards in Lecture 22 - Skeletal muscle mass: mechanisms of hypertrophy Deck (21):
having an episode of acute major disease has a huge impact on...
exercise capacity in the years following
all daily activities will be completed at a higher intensity, more easily tired etc...
a downward spiral
How can you measure AAs in the body and work out if they are being oxidised?
continuous infusion of 13C-labelled AAs
measure the ratio of labelled/unlabelled in plasma
measure 13CO2/12CO2 ratio in breath
More 13CO2 in breath means more oxidation of infused tracer?
How is whole-body protein synthesis and breakdown measured?
constant infusion of labelled AA
measure plasma tracer enrichment against time
At a certain point the increase in labelled AA in the plasma will plataeu
The whole body protein metabolism can be determined from this (not sure if need to know the specifics)
The ____ contributes most to whole body protein turnover
despite the fact that other tissues, liver etc.. have a high synthesis rate
Protein synthesis and breakdown rates are not constant during the day, they are highly responsive to:
Food intake - protein, CHO, fat
With resistance exercise there is a __% increase in protein synthesis after exercise (3 hours)
remain elevated for 48 hours
True or false
mixed muscle protein synthesis is reduced during exercse
but increased for >24h post-exercise in untrained individuals
Resistance exercise increase ______ and _______ protein synthesis
myofibrilar and sarcoplasmic protein synthesis
true or false
Mitochondrial protenin synthesis rate
false, other way around
mitochondrial protein synthesis is favoured in ____ exercise
Exercise training alters the acute response to exercise
that different signalling pathways are activated
Increase muscle protein synthesis (MPS) could be achieved through which two means?
Increasing transcription of mRNA which in turn will lead to protein synthesis
or modify existing mRNA and influence at the translational level
True or False
Increased translation seems to drive increase MPS after exercise
What are the signalling pathways that cause cell/tissue growth and proliferation?
P13K, mTOR, MAPKs
Also signal translation factors causing rapid activation of synthesis of specific proteins
Regulation of mTOR is very complex - just need to know that..
its one of the most important proteins in the regulation of protein synthesis
True of False
During exercise AMPK activity is decrease while mTOR signalling in increased
AMPK activity is increaed while mTOR signalling in decreased
AMPK shuts down alot of energy consuming proteins of wihch mTOR is one.
The effect of exercise on S6K1 is ________ specific.
Fibre type specific
If you block mTOR, what don't you get?
a metabolic response to exercise
What are the alterations in protein metabolism as we age?
initial hypothesis: basal protein synthesis is reduced and breakdown is increased
But this would account for a huge loss in muscle mass - its more like 8-10% per decade
Protein synthetic response to exercise is reduced in the elderly
Protein synthesis rates after physical activity and protein intake are significantly reduced in elderly humans
7 days of bed rest was shown to...
reduced the anabolic response to AA intake