Immunohistochemical Quantification of Fast-Myosin in Upper Hind Limb Muscles of the Pig

Abstract

Using an immunohistochemical microquantification technique, in which frozen sections mounted on glass slides are used as analogues of the antigen precoated wells of the enzyme-linked immunosorbent assay-plates and the structure is well preserved, we examined the contents of fastmyosin isoforms in different portions of 17 hind limb muscles of female Duroc pigs. High fast-myosin levels (more than 200mg/g of total protein) were observed in the gluteus superficialis, gluteus medius, vastus lateralis, biceps femoris and tensor fasciae latae muscles, and low levels (less than 75mg/g) in the gluteus profundus, vastus intermedius and semimembranosus muscles. Fast-myosin-positive fibers were distributed more in the superficial regions than in the deeper regions in the hind limb muscles. The highest population of type I fibers was seen in the vastus intermedius muscle (78%), and the lowest in the gluteus medius muscle (10%). The highest number of type IIA fibers was seen in the rectus femoris muscle (29%), while the lowest was seen in the semimembranosus muscle (14%). The highest number of type IIB fibers was found in the gluteus medius muscle (73%), and the lowest in the vastus intermedius muscle (7%). Good correlation between the microquantification and histochemical analysis was seen. The histological structure of the muscles was well preserved during microquantification, and this technique could be used in research projects to study the contractile properties of the muscles and evaluate the meat qualities of pig muscles. , 8, 42-44, 56). Myofibers are classified into three major types, i.e. type I, IIA and IIB types. Type I, IIA and IIB myofibers correspond to slow-twitch-oxidative (SO), fast-twitch-oxidative-glycolytic (FOG) and fasttwitch-glycolytic (FG) myofibers, respectively42-44, 56). In farm animals, the physiological characteristics of skeletal muscles such as histochemical myofiber type composition are considered to be closely related to meat quality4, 5, 9, 13-18, 24-26, 29, 42, 48, 50-56, 59). Lipids are stored mainly in type I myofibers and in some type IIA myofibers in pigs13) and cattle53), and lipid content is related to shear force of meat13). Myofiber type influences thermal protein aggregation of salt-soluble protein and should undergo different processing treatments for optimum quality of meat products from pigs48). In Japan, marbling score is the most important parameter of cattle meat quality, and the composition of myofiber types of skeletal muscles, longissimus, biceps femoris muscles etc., is related to the Corresponding: Noboru MANABE (fax:+81 (0) 75-753-6345,

Histochemical properties of skeletal muscles in Japanese cattle and their meat production ability

“…Regional differences of myofiber distribution within a muscle are evident in cats (Gonyea & Ericson 1977), pigs (Iwamoto et al 1989;Manabe et al 2001), monkeys (McIntosh et al 1985, sheep (Suzuki & Tamate 1988;Suzuki 1991Suzuki , 1995, rabbits (Vigeneron et al 1976) and horses (López-Rivero et al 1992;Serrano et al 1996). Regional differences have also clarified in the muscles of Japanese Black steers, namely in the Longissimus thoracis and Biceps femoris (cranial head) muscles (Gotoh et al 1994(Gotoh et al , 1995.…”

“…Regional differences of myofiber distribution within a muscle are evident in cats (Gonyea & Ericson 1977), pigs (Iwamoto et al . 1989; Manabe et al . 2001), monkeys (McIntosh et al .…”