ABSTRACT
We have developed a method for estimating the depth and intensity of muscular unit represented as equivalent current dipoles by the inverse analysis of surface electromyograms (EMGs) . In this study, the validity of the locations of current dipoles estimated through the inverse analysis was verified by animal experiments. Surface motor unit action potentials (MUAPs) were recorded from the gastrocnemius muscle activated by electrical stimulation at the ventral root of lumbar spinal cord (L4 or L5) of rats. After recording the surface MUAPs for the inverse analysis and glycogen depletion of active muscle fibers by repeated electrical stimulation, periodic acid-Schiff (PAS) staining was used to determine the position of muscle fibers belonging to an active single motor unit. In the results of the inverse analysis, the values of ‘goodness of fit’ between measured and calculated MUAP were 71%, 79% and 85%. Estimated depths of current dipoles ranged from 1.8 mm to 5.9 mm. The locations estimated through the inverse analysis were more medial and shallower than the actual distribution of active muscle fibers determined by PAS staining. These errors were probably caused by the effects of the boundary in the model, the relationship between the measurement area and the location of an active motor unit, and the artifacts such as deformation of the muscle during dissection and freezing.
ABSTRACT
In this study, the glycogen depletion and repletion of 4 hind limb skeletal muscles which are composed of different type of muscle fibers were investigated in the streptozotocin induced diabetic rats. At sixth day after intraperitoneal injection of streptozotocin (65mg/kg, BW), the plasma insulin level was decreased to 28.2 ±4.16u U/ml comparing with the level of 49.3 ±9.41 in control rats, And it showed approximatly 300% increment of the level of blood glucose concentration in the sedentary diabetic rats. The soleus (slow oxidative), rad gastrocnemius (fast oxydtive glycolytic), extensor digitorum longus (fast oxidative glycolytic and fast glycolytic mixed), and white gastrocnemius (fast gltycolytic) were subjected in this study. The decreased amount of glycogen in the muscles by 3 minutes treadmill running in disbetic rats was larger than that of control rats. The largest amount of depletion was observed in the soleus in diabetic rats. The repleted amount of muscle glycogen was measured at 2 hours after glucose ingestion (25% glucose sol., 2ml/10gm BW). In the control rats, the highest amount of glycogen was repleted in the soleus, but lowest in white gastrocnemius. The repleted amount of glycogen in soleus, red gastrocnemius, and extensor digitorum longus was lower in the muscles of diabetic rats than in control rats, but no difference was observed in white gastroenemius muscles. These data suggest that glycogen synthetic activities of all of muscles except the muscles which are composed of fast glycolytic fiber, were stimulated by insulin.
Subject(s)
Animals , Rats , Blood Glucose , Eating , Extremities , Glucose , Glycogen , Injections, Intraperitoneal , Insulin , Muscle Fibers, Skeletal , Muscle, Skeletal , Muscles , Plasma , Running , StreptozocinABSTRACT
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.