M7 Measuring muscle protein metbolism Flashcards
1
Q
Why are people interested in measuring protein turnover?
A
Hypertrophy vs atrophy
2
Q
How much does protein contribute to the muscular system?
A
- Protein contributes to 50% of the muscular system
- Not the sole source of muscular energy
3
Q
Measuring protein metabolism
A
- Nitrogen balance (in & out)
- Plasma urea/urea in urine
- Only gives general idea about whole body AA utilisation → not an accurate representation
- Until stable isotope methodology came in
4
Q
Stable isotope methodology
A
- Continuous infusion of labelled AA
- Measure ratio of labelled/unlabelled
- ↑13CO2 in breath = more oxidation
5
Q
Effect of exercise and protein intake on AA oxidation
A
- Exercise
- Does not affect phenylalanine oxidation, but ↑leucine oxidation during exercise
- Protein intake
- ↑leucine and phenylalanine oxidation and urea production
6
Q
How is protein synthesis measured?
A
- Take muscle biopsy
- Determine AA in muscle protein
7
Q
What happens to protein synthesis during exercise?
A
- ↓protein synthesis during exercise but ↑ 24hrs post-exercise in untrained individuals
8
Q
Measurement of protein synthesis in different protein fractions
A
- Isolation of different protein fractions from muscle through centrifuge
9
Q
Endurance and Restsiance exercise on myo and mito protein syn
A
- Myo
- Untrained: R > E (no change)
- Trained: R > E
- Mito
- Untrained: E > R
- Trained: E > R (no change)
10
Q
Turnover rates
A
- Each protein has a different turnover rate
- ETC proteins have highest turnover (4x higher than MyHC)
11
Q
sunSET methodology
A
- SunSET methodology → visualise and quantify relative ex vivo and in vivo rates of protein syn
12
Q
Paromycin to measure protein synthesis
A
- Paromycin → structurally similar to tyroxyl-tRNA
- Able to couple it to ribosomes → and thus measure protein turnover rate
