抄録
The effect of local ischemia on the development of muscle pain produced by eccentric exercise was examined in lightly anesthetized rats. A total of 16 rats were allocated to the exercise group (EG) and the ischemic exercise group (IG). For the ischemia, the femoral artery and vein were tied with a thin thread before the exercise. Repetitive eccentric exercise was produced by manual extension of the gastrocnemius (GS) muscle during tetanic contraction elicited by electrical stimulation of the tibial nerve. The development of muscle pain was determined by mechanical withdrawal thresholds (MWT) by Randall-Selitto test to the GS muscle. The focal electrical stimulation (constant current pulses of 1ms in duration) of the GS muscle was successively stimulated at C-fiber strength (10 train pulses, interval: 0.1-1Hz) and flexion reflex activity was recorded from the biceps femoralis muscle. In the EG, the MWT was the lowest value on 1st day after the exercise and then increased gradually to the baseline level on 7th day. On the other hand, in the IG, the MWT was the lowest value on 2nd day after the exercise and then increased gradually to the baseline level on 14th day. The wind-up, the increment of C-fiber responses to the successive stimuli, at 0.5 or 1Hz was only observed on 2nd day after the exercise in the IG. In the present study, the local ischemia elongated the muscle pain until 14th day after the exercise and induced the wind-up phenomena on 2nd day after the exercise. These results suggest that the local ischemia might be a possible cause of development of the chronic muscle pain. [Jpn J Physiol 54 Suppl:S171 (2004)]
