Muscle fiber type composition of the rat hindlimb

Abstract

The purpose of this study was to estimate the absolute and relative masses of the three types of skeletal muscle fibers in the total hindlimb of the male Sprague-Dawley rat (Rattus norvegicus). For six rats, total body mass was recorded and the following weights taken from dissection of one hindlimb: 32 individual major muscles or muscle parts, remaining skeletal musculature (small hip muscles and intrinsic foot muscles), bone, inguinal fat pad, and skin. The fibers from the 32 muscles or muscle parts (which constituted 98% of the hindlimb skeletal muscle mass) were classified from histochemistry as fast-twitch oxidative glycolytic (FOG), fast-twitch glycolytic (FG), or slow-twitch oxidative (SO), and their populations were determined. Fiber cross-sectional areas from the same muscles were measured with a digitizer. Mass of each of the fiber types within muscles and in the total hindlimb was then calculated from fiber-type population, fiber-type area, and muscle-mass data. Skeletal muscle made up 71% of the total hindlimb mass. Of this, 76% was occupied by FG fibers, 19% by FOG fibers, and 5% by SO fibers. Thus, the FG fiber type is clearly the predominant fiber type in the rat hindlimb in terms of muscle mass. Fiber-type mass data are compared with physiological (blood flow) and biochemical (succinate dehydrogenase activities) data for the muscles taken from previous studies, and it is demonstrated that these functional properties are closely related to the proportions of muscle mass composed of the various fiber types.

Spatial distribution of fiber types within skeletal muscle fascicles from Standardbred horses

“…The results showed a predominance of type IIB fibers in the periphery of the fascicles, and of types I and IIA in the more central parts, which also agrees with studies of other mammals (James, 1971a(James, , b, 1972Ariano et al, 1973;Armstrong, 1980;Lexell et al, 1983;Armstrong and Phelps, 1984;Sjøstrøm et al, 1986Sjøstrøm et al, , 1992Hansen et al, 1987;Newsholme et al, 1988;Grotmol et al, 1988;Pernus and Erzen, 1991;Strøm and Holm, 1994). In the present study, type IIB fibers were identified by traditional myosin ATPase histochemistry.…”

Age-related muscle dysfunction

“…Specifically, the soleus muscle is composed of >90% type I fibers, whereas the semimembranosus is composed of >90% type IIB fibers (Armstrong and Phelps, 1984). We used 3-nitrotyrosine (3-NT) as a stable marker of protein oxidative damage.…”

Measurement of contractile force of skeletal and extraocular muscles: Effects of blood supply, muscle size and in situ or in vitro preparation

“…In addition, the surgical preparation does not require removal of facial or cranial bones, which has been the usual protocol for indirect (nerve) extraocular muscle stimulation experiments conducted in mammals (Bach-yRita and Ito, 1966;Barmack et al, 1971;Hanson and Lennerstrand, 1977;Shall and Goldberg, 1992;Dimitrova et al, 2002). For a limb skeletal muscle, the lateral gastrocnemius was selected because it is composed largely of fast muscle fiber types (Armstrong and Phelps, 1984), which is similar to the high percent of fast muscle fiber types found in extraocular muscle. The lateral gastrocnemius muscle can be easily stimulated in situ with wire electrodes in contact with the lateral tibial nerve and has been used frequently for in situ contractile studies (Ameredes and Provenzano, 1997;Grassi et al, 2002;de Haan, 1998;Ma et al, 2004).…”