Neuromuscular stimulation ameliorates ischemia-induced walking impairment in the rat claudication model

Intermittent claudication (IC) is the most common symptom of peripheral arterial disease which significantly deteriorates the quality of life of patients. Exercise training is by far the most effective treatment for IC; however, the underlying mechanisms remain elusive. To determine the local mechanisms by which exercise training improves walking performance in claudicants, we developed an implantable device to locally induce ischemic skeletal muscle contraction mimicking exercise via electrical stimulation (ES). Rats were assigned to four groups, Sham, Ischemia (Isch), Isch + exercise and Isch + ES groups. Following both unilateral femoral and iliac artery occlusion, rats showed sustained impairment of walking performance in the treadmill test. Chronic low-frequency ES of ischemic skeletal muscles for 2 weeks significantly recovered the occlusion-induced walking impairment in the rat claudication model. We further analyzed the ischemic skeletal muscles immunohistochemically following ES or exercise training; both ES and exercise training significantly increased capillaries in the ischemic skeletal muscles and shifted the muscle fibers toward oxidative types. These findings demonstrate that ES takes on common features of exercise in the rat claudication model, which may facilitate investigations on the local mechanisms of exercise-induced functional recovery.