ABSTRACT
The expression levels of heat shock proteins after heat stress on rat slow soleus and fast plantaris muscles were examined and compared during a recovery period following 1 h of heat stress. The left hindlimbs of adult male Wistar rats (n=15) were carefully inserted into a stainless steel can and subjected to heat stress for 1 h by raising the air temperature inside the steel can to 54-58t with a flexible heater so as to bring the muscle temperature up to 42°C. The muscles of the contralateral right hindlimb served as the control. The expression levels of HSP 60, HSP 72, and HSC 73 were analyzed by Western blotting after 0, 2, and 4 h of recovery following 1 h of heat stress. In the soleus muscle, all of the HSP levels analyzed were significantly increased during 0-4 h of recovery. On the other hand, heat stress had no effect on the expression levels of HSPs, except HSP 60, in the plantaris muscle during recovery after 1 h of heat stress. These results suggest that the slow soleus muscle has a higher ablility to respond quickly to heat stress than the fast plantaris muscle.
ABSTRACT
The running behavior and muscle characteristics associated with voluntary running activity were studied in female Fischer 344 rats after 9 weeks of training in voluntary exercise wheel cages. The exercise wheel employed allowed a load to be added to the wheel axis. The running activity was recorded as the number of rotations every 10 s for 24 h, and the number of running bouts, running duration, running speed and distance run per day were varied. Addition of a load to the wheel axis allowed the running style to be changed, and reduced the running duration and speed in each bout. The voluntary running training was done with no load, 30% per body weight load, and 60% per body weight load, and as treadmill running (40 m/min, 60 min/day) .<BR>In the voluntary training, a difference in the total running distance was observed with increased load. The total distance run under 0%, 30% and 60% load in the voluntary group was about 552, 475, and 438 km, respectively, after training for 9 weeks. As a result of training, the weights of dorsiflexor muscles tended to increase with treadmill running, whereas weights of plantar-flexor muscles increased significantly in the voluntary training groups. In the plantaris muscle, the cross-sectional area of all fiber types was not changed by treadmill training, but in voluntary training, almost every type of fiber was enlarged. Voluntary running with a 30% load increased the cross-sectional area of type I and type ha fibers in the plantaris muscle compared with no load exercise. However, no significant differences in the cross-sectional area of these fibers were observed between 30% and 60% load exercise. The fatigue tolerance of the plantaris muscle improved significantly in all training groups, and the 60% load group showed the highest value.<BR>These results suggest that voluntary loaded running is more effective for muscle enlargement than treadmill training and/or voluntary training with no load.
ABSTRACT
To determine whether fiber type-specific expression of heat shock protein (HSP, or stress protein) occurs in unstressed rat skeletal muscle, the medial gastrocnemius of adult female Sprague-Dawley rats was subjected to immunohistochemical analysis. Antibodies against 5 types of anti-myosin heavy chain (MHC) were used to classify the type of fibers, and 2 types of anti-HSP antibodies were employed to analyze the fiber type-specific expression.<BR>Serial cross-sections of 10 μm thick cut by a cryostat were incubated with primary anti-MHC or anti-HSP 60 and 72 antibodies, followed by biotinylated secondary anti-mouse antibodies, and avidin-biotin complex solution. A peroxidase DAB substrate kit (Vector SK-4100) or BCIP/NBT solution was used to visualize the immunoreaction of each fiber type.<BR>By using the 5 types of anti-MHC antibodies, fibers were classified into 4 types : slow-type I, fasttypes IIA, IIX, and IIB. Anti-HSP 72 antibody reacted with many, but not all, type I and IIA fibers, whereas anti-HSP 60 antibody reacted specifically with type I fibers. Neither type IIX nor IIB fibers showed immunoreactivity with anti-HSP 60 or 72 antibodies. These results suggest that the expression of HSP 60 protein is related to that of type I MHC, and that the expression of HSP 72 protein may be related to that of types I and ha MHC, in unstressed rat skeletal muscle.
ABSTRACT
Thirty (n=30) seven week old male Sprague-Dawley rats were divided into six groups of five rats (n=5) in each group. The groups were designated Sc=sea level controls; St=sea level trained; Fc=hypoxic exposed (16% O<SUB>2</SUB>) controls; Ft =hypoxic exposed (16% O<SUB>2</SUB>) trained; Pc=intermittent hypoxic exposed (18%, 16%, 14%, 16%, 18% O<SUB>2</SUB> for two days each) controls; and Pt=intermittent hypoxic exercise trained. Exercise training consisted of 45min/day running on a rat treadwheel for 24 consecutive days. Fiber type distribution, succinate dehydrogenase (SDH) activity and glycogen content of the soleus muscle and the oxidative enzyme activity of the motoneurons of the soleus were measured in each group after the 24 days of hypoxic exposure and exercise training. In comparison to each training group's control the glycogen concentration of the soleus muscle was increased (P<0.05) regardless of hypoxic exposure. Only the intermittently hypoxic exercise trained group (Pt) demonstrated a fiber type shift of slow-twitch oxidative to fast-twitch oxidative glycolytic fibers. Neither hypoxia or exercise training altered the oxidative enzyme capacity of the soleus motoneurons.
ABSTRACT
The present study was undertaken in order to investigate effects of short-term, high intensity training on the total number and histochemical properties of fast tibialis anterior, slow soleus muscle fibres and their dominant motor neurons in male rats.<BR>The animals were subjected to 4 meters of sprint-running by the operant conditioning, 12 times a day interposed with 5 minutes rest periods for 14 weeks.<BR>This training had no effect on the total number and enzyme activities of muscle fibres and dominant neurons. However, hypertrophy of FOG and FG fibres in tibialis anterior muscle was caused by the training.<BR>The conclusion, therefore, is that short-term but high intensity training causes selec. tive hypertrophy of fast twitch muscle fibres, but does not have an influence on the histochemical properties of motor units because the training is far a short period of time.
ABSTRACT
The purpose of this study was to investigate effects of intermittent running trainings with trot and gallop on glycogen consumption patterns of antagonistics (m. gastrocnemius and m. tibialis anterior) in male Wistar strain rats (4 weeks after birth, n=46) . The animals were devided into three groups, control (n=18), trot training (n=14), and gallop training (n=14) . In order to evaluate glycogen consumption patterns, serial sections of the muscles were stained for Myosin ATPase, DPNH-diaphorase, and Periodic acid-Schiff (PAS) reaction.<BR>The results were summarized as follows ;<BR>1) Significant change in fiber distribution occurred on both training groups, where the percentage of FOG fiber increased and there was a concomitant decrease in the FG fiber percentage. On the gallop tiaining group this effect was shown in the deep and peripheral regions of both muscles, but on the trot training group that wasn't shown in the peripheral region of m. tibialis anterior.<BR>2) According to glycogen depletion patterns after transient running exercises, during gallop the participation of m. tibialis anterior was shown a tendency to increase.<BR>3) With the trainings, decrease of glycogen consumption in muscle fiber occurred in deep and peripheral regions of the both muscles on gallop training group and in the m. gastrocnemius on trot training group.<BR>These results suggest that the trainings with different running forms have different effects on the antagonistics.
ABSTRACT
Wistar strain male albino rats were sacrificed at 1, 3, 5, 7, 9, 11, 13, 15, 17, 19 and 21 days of age, and the histochemical properties of nerve cell and muscle fibre were examined.<BR>We obtained the following differentiation process in the muscle with postnatal growth;<BR>phase I (newborn-7 days) undifferentiated fibre<BR>phase II (7-15 days) FT fibre ST fibre<BR>phase III (after 15 days) FG fibre FOG fibre SO fibre<BR>On the other hand, histochemical differentiation of nerve cell was recognized earlier than that of muscle fibre, and there was no redistribution of soma type with growth.<BR>Therefore, it may be said bhat histochemical differentiation process in the muscle is largely effected by the neuronal influences exerted from the lower motoneurons.