LECTURE 26 Flashcards
What does the success of regeneration depend on?
The level of fibrosis
What happens with ageing?
Inflammatory marker expression is prolonged, TNF and IL-6 are higher, excessive inflammatory response comprises successful muscle repair
When are satellite cells dominant?
Pre-injury
What is the regeneration timeline?
- begins by 5 days
- damaged muscle fibre degraded and satellite cells activated
- myoblasts fuse to form myotubes with maturity gradient (1-2 weeks)
- myofibrilogenesis
What is the basal lamina function and what happens if it is damaged?
Scaffold for myoblast alignment.
Damaged: myotube formation is impaired
What is the maturity gradient?
Most advanced fibres are at surviving fibre stumps and less mature are at the centre of injury
What does the rate of regeneration depend on?
Extent of injury, muscle injured, animal model, differential expression of transcription factors
What happens to muscles moved from old rats to young rats?
Regenerate at similar rate to young rats
What happens to muscles moved from young rats to old rats?
Regenerate at similar rate to old rats
What is the major determinant of quality of regeneration?
Host environment
What things are reduced with ageing that contribute to reduced environment for regeneration?
Physical activity, trophic and neural support and growth factors
What state are most muscle fibres in when uninjured?
Type I
What state are most muscle fibres in when injured (bupivacaine)?
Type IIa
When rats are injected with bupivacaine what are the muscle changes?
7 days: slow muscle has fast characteristics and fast muscle has slow characteristics
14 days: fibre phenotype is normal
When does true functional restoration occur, and what muscle type takes longer to repair?
60 days, slow muscle takes longer to repair
