Frequency response of nerve-muscles relating to fatigue and hypokalemia in rats

The study of nerve-muscle is an important issue in extensive research fields such as engineering and bioengineering. This paper examines differences between normal and hypokalemic nerve-muscle, useful as a nerve-muscle disease model, under both rest and muscle fatigue conditions. The association between nerve stimulation frequencies (11 stimulations, pulse duration 50 μ sec, 0.5-200 Hz) and electromyogram (EMG) amplitude was studied using rat nerve muscle, based on control theory and physiology. The EMG was recorded from soleus (SOL; slow twitch fiber type model) and extensor digitorum longus (EDL; fast twitch fiber type model) in vivo. It was found that SOL and EDL had different breakpoint frequencies of about 15 and 85 Hz respectively in normal rats, and each muscle break point frequency decreased to about 5 and 15 Hz in hypokalemic rats. All of them had 1/f properties in fatigue. The results of these experiments suggested that frequency responses of the nerve-muscle were affected by the type of fiber, the degree of nerve-muscle disease and fatigue. Further research is needed on nerve-muscle under various conditions to evaluate the possibility of applying the nerve-muscle system to control theory