Effect of motor neuromuscular electrical stimulation on microvascular perfusion of stimulated rat skeletal muscle

The purpose of this study was to determine the effect of neuromuscular electrical stimulation (NMES) (2,500-pps sine wave interrupted at 50 bps) on the degree of microvascular perfusion in stimulated skeletal muscle. The tibialis anterior (TA) and extensor digitorum longus (EDL) muscles of 36 male rats were treated with NMES for 30 minutes at current amplitudes sufficient to produce a sustained muscle contraction (motor NMES). Muscle tissue was removed at 0, 5, 10, 15, and 30 minutes after NMES. The perfused vessel/muscle fiber ratio (PV/F) of the stimulated animals at time 0 minutes was greater than that of the unstimulated control animals. A gradual decrease in the magnitude of the PV/F increase was noted over time. Depending on the muscle's fiber-type composition, the PV/F values returned to control levels by 10 to 30 minutes after motor NMES. The results indicate (1) that motor NMES significantly increases the degree of microvascular perfusion in stimulated rat skeletal muscle and (2) that the increased degree of perfusion persists for various lengths of time, depending on the fiber-type composition of the muscle. Thus, if responses in an animal model can be used as indicators of similar human responses, then the results of this study suggest that NMES can be used to increase the degree of microvascular perfusion in human skeletal muscle.