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FRONTIERS IN PHYSIOLOGY > Muscle 9 > Flashcards

Flashcards in Muscle 9 Deck (17):
1

What is the protein balance responsive to?

Anabolic stimuli

2

What amount of protein is enough to maximally stimulate protein synthesis?

25g

3

What effect does AA infusion have?

Rapidly increases protein synthesis - but 2hr later it returns to baseline

4

How do essential amino acids stimulate protein synthesis?

mTORC1

5

What are the downstream targets of mTORC1?

4EBP1 and S6K

6

How does arginine stimulate protein synthesis?

mTOR dependent manner – if rapamycin is present, arginine will not be able to increase protein synthesis

7

Where do AAs need to be to increase protein turnover and synthesis?

Extracellular space

8

What does mTOR need to be active?

Translocate to a lysosome

9

What are some anabolic interventions?

Resistance exercise
AA intake

10

How does mTOR become active?

Insulin -Akt -mTOR-lysosome

11

What is important for leucyl tRNA?

couples leucine to tRNA - used by ribosome to build new proteins

Has GTPase activity - when activated by leucine can activate mTOR

12

What is SLC389A part of?

Lysosomal aa machinery that controls mTOR (responds to arginine)

13

Do protein supplements fix protein synthesis levels in elderly?

No - they aren't responding to leucine so more leucine won't fix the problem

14

What is changed in the elderly?

Total mTOR is reduced in elderly, more inflammatory signalling (increased NKB) and reduced response to essential AAs

15

Does increased CHO intake improve protein synthesis?

No

16

How much CHO can be oxidised per hour and what can increase this?

Only 60g of CHO can be oxidised per hour - if you combine glucose and fructose you can further increase CHO oxidation and reduce glycogen use during exercise - improve performance

17

What happened to rats on a sucrose diet?

Lose more muscle during ageing and lower rates of protein turnover