P-2-08-01
HISTOCHEMICAL PROPERTY OF RAT QUADRICEPS FEMORIS MUSCLE
T. Furuichi, F. Eto, K. Shibuya (Dept. of Rehabil., Dokkyo Univ. School of Med., Tochigi, Japan) T. Harada (Dept. of Orthop. Surg., Toho Univ., Tokyo, Japan)
The purpose of this study was to examine the histochemical properties of rat intact quadriceps femoris muscle in the superficial, intermediate and deep layer of muscles.
Twenty white adult female rats of a Wistar strain, each weighing 240-280gr, were used in this study. Quadriceps femoris muscle (rectus femoris, vastus lateralis, vastus medialis and vastus intermedius) were rapidly removed from the animal and frozen in an acetone and dry-ice mixture at -60℃, allowed to warm to -20℃ in a cryostat. Fresh frozen serial cross-sections (10μm thick) were mounted on glass slides and were stained with hematoxylin eosin and ATPase activities. Myosin ATPase was used to differentiate type I (slow) and type II (fast) fibers. The quadriceps femoris muscle had marked regional variation in proportions of type I (red, slow) fiber and type II (white, fast) fiber content. Histochemical examination corroborated the impression obtained on gross visual inspection. It was found that one-joint muscle (vastus medialis and vastus intermedius) had higher proportion of the type I fibers. Rectus femoris muscle (two- joint muscle) had higher proportion of the type II fibers, the dynamic phasic muscles. It was clear that the size of type II fibers in superficial layer of the muscle was larger than that in the deep layer. It was also apparent that the mean diameter of type I fibers in the deep layer of the muscle was larger than that in the superficial layer.
P-2-08-02
EFFECTS OF AGING ON ENERGY METABOLISM OF RAT HINDLIMB MUSCLES BY PHOSPHORUS-31 MAGNETIC RESONANCE SPECTROSCOPY
Shinjiro Takata, Takaaki lkata, Hiroaki Takai, Yoshihiro Hayashi, Tetsuya Matsuura (The University of Tokushima, Tokushima, Japan)
The purpose of this experiment was to clarify the effects of aging on energy metabolism and muscular function of rat hindlimb muscles. Energy metabolism was assessed by phosphorus-31 magnetic resonance spectroscopy and muscular function was evaluated by a strain gauge. Five young (25 weeks old) Wistar Kyoto (WKY) and old (92 weeks old) male WKY rats were used in this experiment. Initial tension of hindlimb muscles of the old rats was approximately 55% of that of the young rats [383.4±40.0 (S.E.) dynes versus 211.1±12.5 (S.E.) dynes; p<0.05] . Later, tension decreased without significant difference between the two groups. In the 2 minutes of stimulation, the phosphocreatine (PCr)/{inorganic phosphate (Pi) + sugar phosphate (SP)} ratio and the intracellular pH in both young and old rats declined to their minimums. From 12 min to 16 min of stimulation, the PCr/(Pi+SP) ratio and intracellular pH of young rats were significantly higher than those of old rats (p<0.05). During and after stimulation, the rate of recovery of the PCr/(Pi+SP) ratio and intracellular pH in the young rats were higher than those in the old rats. The obtained results in this experiment showed that aging induced a low initial tension, low energy level and intracellular pH with a slow recovery of the energy level and of the intracellular pH of skeletal muscle.
