This study was designed to evaluate the effect of intermittent electrical stimulation on atrophied masseter muscle in the rat(230-250g). Growing Sprague-Dawley rats(80g) were assigned to either a control(CONT), a soft dieted(SOFT), or a soft
dieted
plus
intermittent electrical stimulation(SOFT-ES) group. CONT group was continued to receive an ordinary hard rat diet and SOFT group received an ordinary diet in a ground form, mixed with water in a proportion of 2:5, for 6 weeks. After 6 weeks of
soft
diet
feeding in SOFT group, mechanical properties of contraction in the masseter muscle were measured by means of isometric force transducer and then electrodes were implanted to the masseter muscle for intermittent electrical stimulation(SOFT-ES
group). In
SOFT-ES group, electrical stimulation was applied directly to the maseter muscle for 2 weeks at supramaximal intensity, 0.3ms, 20Hz for 15 minutes every 6 hours. After electrical stimulation for 2 weeks, mechanical properties and fatigue tendency
of the
masseter muscle were observed.
@ES The results were as follows.
@EN 1. Twitch tension was no significant difference according to the mandibular position, however, tetanic tension at 11mm interincisal distance was larger than at 7mm.
2. In SOFT group, tetanic tension and contraction time were decreased, and fatigue tendency was increased compared with the control group.
3. In SOFT-ES group, tetanic tension was increased and fatigue tendency was decresed compared with the soft dieted group, however, all mechanical properties of muscle contraction were similar to those of the control group.
4. Effects of electrical stimulation in atrophied muscle were more prominant in tension-related properties than speed-related properties.
These data suggest that intermittent electrical stimulation may be useful in prevention and treatment of muscle atrophy.
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