Muscle 7

Question 1

What determines the amount of muscle mass lost or gained?

Answer 1

Balance between protein synthesis and breakdown

Question 2

How much free floating amino acid and protein in a person?

Answer 2

70g amino acids

10kg of protein

Question 3

What is the rate of protein synthesis and breakdown per day?

Answer 3

300g/day of each process if in balance

Question 4

What is the rate of protein intake and oxidation per day?

Answer 4

80g/day of each

Question 5

What did Jutus Von Liebig propose?

Answer 5

In 1840 he proposed that protein is the fuel for muscle contraction

Question 6

What % of muscular energy is contributed to by protein?

Answer 6

50%

Question 7

What does more CO2 in the breath after AA infusion mean?

Answer 7

More oxidation

Question 8

What does exercise cause?

Answer 8

Exercise does not increase urine production or phenylalanine oxidation, but it does increase leucine oxidation

Question 9

What does protein intake cause?

Answer 9

Protein intake increases leucine and phenylalanine oxidation and urea production

Question 10

When is muscle protein synthesis highest?

Answer 10

Lowest during exercise and increased for 24-48 hours post exercise

Question 11

What does resistance exercise increase?

Answer 11

Myofibrilar and sarcoplasmic protein synthesis

Question 12

What happens to FSR following exercise training?

Answer 12

Mitochondrial FSRR > myfibrilar FSR

Question 13

What does endurance exercise lead to over time?

Answer 13

Increased mitochondrial protein turnover

Question 14

What chain has the highest protein turnover?

Answer 14

ETC - 4x higher than myosin heavy chain

Question 15

What structure is similar to puromycin?

Answer 15

Tralyl tRNA

Question 16

What does puromycin increase and what is different about this in tumour bearing mice?

Answer 16

Puromycin increases protein synthesis but in tumour bearing mice there is no increase in protein turnover (anabolic resistance)

Question 17

What are the observational end point measures in health and disease?

Answer 17

• Ageing/disease is associated with a loss in muscle mass

- Ageing/disease is associated with a reduction in the anabolic (protein synthesis) responses to food intake

Question 18

What mediates increased protein synthesis following leucine intake?

Answer 18

Activation of mTOR in a leucyl-tRNA synthetase dependent manner

Question 19

What is the action of rapamycin?

Answer 19

mTORC1 - protein synthesis

Question 20

How do essential amino acids stimulate protein synthesis?

Answer 20

Increased signalling through mTORC1 and activation of mRNA translation

Question 21

What does Akt do?

Answer 21

Regulates protein breakdown and the akt/mTOR pathway is involved in regulation of protein breakdown and the initiation of translation initiation

Question 22

How does mTOR act?

Answer 22

mTOR phosphorylates 4E-BP1 allowing ribosomal complex formation

Question 23

How is compensatory hypertrophy mediated?

Answer 23

Increased signalling through Akt