A New System and Paradigm for Simultaneous Chronic Stimulation of Denervated Muscle in Multiple Animals

Abstract

Traditionally, animal studies employing electrical muscle stimulation for conditioning denervated muscle rely on implantable stimulators and 24 hour based stimulation paradigms. While these stimulators provide the necessary current to cause muscular contraction, they have problems with battery life, programmability, and long term robustness. Continuous 24 hour stimulation, while shown to be effective in animals, is not easily translatable to a clinical setting. It is also difficult to evaluate animal comfort and muscular contraction throughout a 24 hour period. We have developed a system and stimulation paradigm that can stimulate up to five animals at one time for one hour per day. The constant current stimulator is a USB powered device that can, under computer control, output trains of pulses with selectable shapes, widths, durations and repetition rates. It is an external device with no implantable parts in the animal except for the stimulating electrodes. We have tested the system on two groups of rats with denervated gastrocnemius muscles. One group was stimulated using a one hour per day stimulation paradigm for one month, while the other group had electrodes implanted but received no stimulation. Muscle weight and twitch force were significantly larger in the stimulated group than the non-stimulated group. Presently, we are using the stimulator to investigate electrical stimulation coupled with other therapeutic interventions that can minimize functional deficit after peripheral nerve injuries.