Fibre type regionalisation in lower hindlimb muscles of rabbit, rat and mouse: a comparative study

Abstract

The topographical distribution of different fibre types in muscles of the lower hindlimb in rabbits and mice was quantitatively determined. The results were compared to those previously obtained, using the same new quantification methods, in homologous muscles of the rat. Type I fibres (' slow ') were identified using myofibrillar ATPase histochemistry and mapped out at the mid proximo-distal level for 11 ' fast ' muscles in the rabbit and 7 ' fast ' muscles in the mouse. For the slow soleus muscle the procedure was undertaken for the type II fibres. Furthermore, for 5 of the ' fast ' muscles from each animal species (extensor digitorum longus ; flexor digitorum and hallucis longus ; gastrocnemius medialis ; peroneus longus ; tibialis anterior), several more proximal and distal cross-sectional levels were also analysed. All the investigated ' fast ' muscles showed a significant degree of topographical eccentricity in the midlevel distribution of type I fibres. For most muscles, the direction of this ' vector regionalisation ' of type I fibres was similar between the three animal species. For homologous muscles, the degree of vector regionalisation was significantly different : mouse rat rabbit. The relative area of the region containing the type I fibres, inversely related to the degree of ' area regionalisation ', was also significantly different : mouse rat rabbit. Also within each animal species, muscles with a marked degree of vector regionalisation tended to show a marked area regionalisation. Proximo-distal differences in type I fibre density were observed in all the three species of animals ; also these patterns showed marked inter-species differences. The findings demonstrate the general occurrence of, and systematic relationships between, different aspects of type I fibre regionalisation. The observed interspecies differences suggest that the expression of this phenomenon is adapted to differing functional needs.

Distribution Pattern of Muscle Fiber Types in the Perivertebral Musculature of Two Different Sized Species of Mice

“…Fiber size has also been suggested to depend on the sample location along the longitudinal axis, that is, proximo-distal, as well as along the transversal axis, that is, deep to superficial of limb muscles (e.g., English and Letbetter, 1982;Armstrong and Phelps, 1984;Totland and Kryvi, 1991;Brandstetter et al, 1997;von Mering and Fischer, 1999;Wang and Kernell, 2001;Punkt, 2002). Our results from this and previous studies (Schilling, 2005;Moritz et al, 2007) confirm these observations for the mammalian axial musculature.…”

Measurement of kinetic parameters in skeletal muscle by magnetic resonance imaging with an intravascular agent

“…This is consistent with the physiological differences between the two muscles. The SOL muscle is comprised primarily of "slow-twitch" type I fibers and is more vascularized than the TA muscle, which consists mostly of "fast-twitch" type II fibers (32). The SOL muscle therefore has a larger capillary surface area.…”

American Thyroid Association Guide to Investigating Thyroid Hormone Economy and Action in Rodent and Cell Models

“…However, in rodents some hind limb muscles are primarily composed of slow type I and intermediate type IIA fibers, such as the slow-twitch soleus (SOL) muscle, or fast type IIB fibers, such as the fast-twitch extensor digitorum longus (EDL) muscle (681,682). These muscle are therefore often used as models to study the effects of thyroid hormone on slow and fast muscle properties.…”

“…Serial cryosections can be used to correlate MHCbased fiber typing with immunohistochemistry of SERCA1a and SERCA2a (676,682), as well as with isoform-specific mRNAs by in situ hybridization (676). Fiber-specific differences in total SR Ca 2 + -ATPase activity can also be determined histochemically (676).…”

“…It should be noted that not all fibers necessarily run the length of the muscle. This is for example the case in SOL muscle, which should preferably be sectioned at the motor point to include all fibers (682,702).…”