Prox1 gene transfer into fast muscles converted them towards the slow fiber
type in mice, whereas Prox1 deletion increased the activity of fast fiber genes.
In the mdx mouse, PGC-1[alpha] overexpression in skeletal muscle also results in a fast to slow fiber
type shift, a restoration of in vitro muscle function, and attenuation of muscle injury .
Further, the additional fast to slow fiber
shift and eMHC-positive fibers suggested differences in the loading and remodeling of the parasternal intercostals.
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Several studies have shown that calcineurin controls the skeletal muscle fiber type by stimulating slow muscle gene promoters and slow fiber
differentiation both in cultured cells and in vivo (Chin et al.
The cephalocarid abdominal muscle has sarcomeres of 5 [mu]m, suggesting a slow fiber
type; this is in keeping with the relatively slow movements of the abdomen.
In scientific literature, data on this problem are poor, but begin to leave to catch a glimpse of hope for a transformation of slow fibers
in fast fibers.
For example, low-intensity and longduration physical training may induce a conversion from fast to slow fibers
can be further divided into at least two groups: [S.
16) Humans have genetically determined mixtures of fast and slow fibers
In the plantaris muscle of cats, slow fibers
have 25 to 50% more myonuclei in a longitudinal section and a smaller average myonuclear domain size compared with fast fibers (Allen et al.
A study associating age and modification in fiber types in swine aged 6-18 months revealed that slow fibers
decreased in both rectus abdominis and vastus medialis muscles, and slow fibers
were more numerous in the vastus medialis muscle.