Author(s): UNO, H., KAMIYA, S., AKIMOTO, R., HOSOKI, K., TADANO, S., ISEMURA, M., KOUZAKI, K., TAMURA, Y., KOTANI, T., NAKAZATO, K., Institution: NIPPON SPORT SCIENCE UNIVERSITY, Country: JAPAN, Abstract-ID: 761

INTRODUCTION:
Electrical muscle stimulation (EMS) induces muscle hypertrophy and inhibits atrophy. EMS is thought that pad electrodes are most often used in clinical practice. However, it is difficult to activate multiple muscle groups simultaneously and efficiently as in voluntary exercise, because the electrodes are usually placed on the target muscle and current can only be applied to a single muscle, making it difficult to exercise multiple muscle groups simultaneously and obtain the effect of suppressing muscle atrophy. Recently, a method called Belt Electrode Skeletal Muscle Electrical Stimulation (B-SES) has been considered to be effective in addressing the problems of pad electrodes. This is an electrical stimulation method that can stimulate multiple muscle groups simultaneously. In addition to being able to stimulate multiple muscle groups simultaneously, the electrode area is larger than that of a pad electrode, resulting in a smaller amount of current per unit area (current density) and an increase in the maximum threshold value that can be tolerated when energized, thus enabling more intense stimulation. Although the clinical usefulness of B-SES has been demonstrated, its molecular mechanism remains unclear. In this study, we developed a novel rodent B-SES ankle stimulation system to test whether tetanus stimulation prevents muscle atrophy caused by denervation and examined the effect of B-SES on preventing muscle atrophy.
METHODS:
Ten-week-old male SD rats were divided into an untreated control group (CONT), denervation group (DEN), and denervation and electrical stimulation group (DEN+ES). DEN+ES rats wore belt electrodes on both ankles and were energized between the two electrodes. Electrical stimulation was applied once two days for 7 days under isoflurane inhalation anesthesia, beginning immediately after denervation, at a frequency (60 Hz) that induces tetanus in rats for 5 minutes (5s on 2s off cycle). Twenty-four hours after the last electrical stimulation, the rats were bled to death under anesthesia, and the tibialis anterior and gastrocnemius muscles were removed bilaterally.
RESULTS:
After 7 days of denervation, muscle wet weight (n=8~11) and muscle fiber cross-sectional area (CSA, n=6) of tibialis anterior and gastrocnemius muscles were lower in DEN and DEN+ES than CONT showed atrophy but were significantly higher in DEN+ES than DEN, showing atrophy prevent. In 18s and 28S ribosomal RNA, DEN+ES was significantly higher than CONT and DEN in the tibialis anterior and gastrocnemius muscles.
In addition, mRNA levels of muscle proteolytic signals, Atrogin-1 and Murf1, were greatly increased by denervation compared to CONT, while B-SES suppressed their expression (p<0.05).
CONCLUSION:
Tetanus stimulation of both rat ankles with belt electrodes may effectively prevent denervation-induced atrophy in multiple muscle groups by sciatic nerve transection via enhancement of muscle protein synthesis and prevention of muscle proteolysis.