EFFECTS OF ELECTRICAL STIMULATION ON RAT MUSCLE FIBERS
Naofumi Tanaka, Yasutomo Okajima, Akio Kimura, Ken Kondo, Kunitsugu Kondo (Tsukigase Rehab. Ctr., Keio Univ., Japan), Kiyoshi Minco (Shizuoka City Hospital, Japan), Shigeto lkeda, Yutaka Tomita (Faculty of Science & Technology, Keio Univ., Japan), Naoichi Chino (Department of Rehab. Med., Keio Univ., Japan)
Effects of electrical stimulation on muscle fibers in rats were morphologically studied. The left tibialis anterior (TA) muscles of three groups of rats was stimulated electrically at 10 Hz for 8 hours per day for the periods of one, two and three weeks. Stimulators were implanted in the rats, and the electrode was placed directly on the left TA muscle belly and the right TA was served as control. Electrical energy was supplied magnetically from outside the cage. The mean weight of the stimulated TA muscles was significantly increased than that of the control side. Histochemical examinations showed that the mean diameters of each muscle fiber in the stimulated muscles were larger regardless of the fiber type than those of the control. These findings were remarkable in the type 2B fibers that were stimulated for three weeks. These results suggest that the period of the electrical stimulation must be the important factor determining changes of fiber diameter and its type.
EFFECT OF PHENTOLAMINE ON THE SPONTANEOUS ELECTRICAL ACTIVITY OF RESPONSIVE LOCI IN A MYOFASCIAL TRIGGER SPOT OF RABBIT SKELETAL MUSCLE
Jo-Tung Chen (National Cheng-Kung University Hospital, Tainan, TAIWAN) Shu-Min Chen, Ta-Shen Kuan, Chang-Zern Hong
This study is designed to investigate the effectiveness of sympathetic blocking agent, phentolamine, on the spontaneous electrical activity (SEA) which is characteristic of a locus in the myofascial trigger point (TrP) region.
SEA were recorded from biceps femoris muscle of adult albino rabbit before and immediately after an injection of phentolamine hydrochloride (1 mg/kg) into the external iliac artery, followed by flushing with normal saline in experimental group. Control study was performed with similar procedure except that normal saline instead of phentolamine was used. The amplitude of SEA was assessed for the comparison of the phentolamine effects between the experimental and control groups. Result:
It was found that the amplitude of SEA was obviously lower after phentolamine injection as compared to that before the injection. The average integrated areas of SEA was significantly lower after phentolamine injection than that after normal saline injection.
This study further support the hypothesis that autonomic nervous system is involved in the pathogenesis of myofascial TrP).