Extracellular stimulation with human "noisy" electromyographic patterns facilitates myotube activity

Area of Science:

• Biomedical Engineering
• Muscle Physiology
• Electrophysiology

Background:

• Electrical stimulation (ES) partially mimics physical activity benefits for skeletal muscle.
• Current clinical ES protocols can cause discomfort and muscle fatigue.

Purpose of the Study:

• To compare the efficiency of a novel "noisy" stimulus waveform (EMGstim) with conventional ES methods.
• To assess EMGstim's effectiveness in activating mouse myotubes in vitro.

Main Methods:

• EMGstim waveform derived from human electromyography (EMG) during locomotion.
• In vitro assessment using mouse myotubes with patch-clamp, Ca(2+) imaging, and optical visualization.
• Comparison with stereotyped 45 Hz and 1 Hz ES protocols.

Main Results:

• EMGstim demonstrated higher efficiency in inducing myotube cell firing, intracellular Ca(2+) changes, and contractions.
• EMGstim required significantly lower stimulation intensity compared to conventional ES.
• The "noisy" stochastic pattern proved more effective than stereotyped stimulation.

Conclusions:

• Muscle cells can be more efficiently depolarized using stochastic stimulation patterns like EMGstim.
• This finding suggests a potential method to increase electrical activity in a larger number of muscle cells.
• EMGstim offers a promising alternative to conventional ES for muscle activation with potentially fewer side effects.