Muscle 7 Flashcards
What determines the amount of muscle mass lost or gained?
Balance between protein synthesis and breakdown
How much free floating amino acid and protein in a person?
70g amino acids
10kg of protein
What is the rate of protein synthesis and breakdown per day?
300g/day of each process if in balance
What is the rate of protein intake and oxidation per day?
80g/day of each
What did Jutus Von Liebig propose?
In 1840 he proposed that protein is the fuel for muscle contraction
What % of muscular energy is contributed to by protein?
50%
What does more CO2 in the breath after AA infusion mean?
More oxidation
What does exercise cause?
Exercise does not increase urine production or phenylalanine oxidation, but it does increase leucine oxidation
What does protein intake cause?
Protein intake increases leucine and phenylalanine oxidation and urea production
When is muscle protein synthesis highest?
Lowest during exercise and increased for 24-48 hours post exercise
What does resistance exercise increase?
Myofibrilar and sarcoplasmic protein synthesis
What happens to FSR following exercise training?
Mitochondrial FSRR > myfibrilar FSR
What does endurance exercise lead to over time?
Increased mitochondrial protein turnover
What chain has the highest protein turnover?
ETC - 4x higher than myosin heavy chain
What structure is similar to puromycin?
Tralyl tRNA
What does puromycin increase and what is different about this in tumour bearing mice?
Puromycin increases protein synthesis but in tumour bearing mice there is no increase in protein turnover (anabolic resistance)
What are the observational end point measures in health and disease?
- 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
What mediates increased protein synthesis following leucine intake?
Activation of mTOR in a leucyl-tRNA synthetase dependent manner
What is the action of rapamycin?
mTORC1 - protein synthesis
How do essential amino acids stimulate protein synthesis?
Increased signalling through mTORC1 and activation of mRNA translation
What does Akt do?
Regulates protein breakdown and the akt/mTOR pathway is involved in regulation of protein breakdown and the initiation of translation initiation
How does mTOR act?
mTOR phosphorylates 4E-BP1 allowing ribosomal complex formation
How is compensatory hypertrophy mediated?
Increased signalling through Akt
