Effects Of Chronic Electric Stimulation Using Ultra-low And Physiologic Frequencies On Diaphragmatic Structure And Function In Rabbits With Emphysema

Chronic obstructive pulmonary disease (COPD) is a disorder characterized by progressive, chronic limitation of airflow. Meanwhile, it is a common, prevalent pulmonary disease. Till now, effective therapy for it is unavailable.Functional impairment of diaphragmatic muscle is one of the pathological hallmarks of COPD. COPD patients frequently develop diaphragmatic muscle fatigue to result in respiratory impairment. Diaphragmatic muscle fatigue may be prevented and treated by medications for ameliorating diaphragmatic muscle contractility, mechanical ventilation to help diaphragmatic muscle rest, respiratory muscle exercise, and diaphragmatic muscle pacing [1-2].Chronic electric stimulation (CES) using physiologic frequency (40Hz) has exhibited certain therapeutic role in the rehabilitation care of diaphragmatic muscle of COPD patients. The use of diaphragmatic muscle pacing is based on the experimental evidence that diaphragmatic muscle, like skeletal muscles, undergoes adaptive changes under electric stimulation. Electric stimulation using various frequencies may cause varying changes in the structure, metabolism and function of skeletal muscles. Diaphragmatic muscle, being skeletal muscle, may undergo adaptive changes similar to those changes of skeletal muscles under chronic electric stimulation.Recently, it has been shown [3-4] that patients with mild to moderate COPD present with atrophy of type I and type II diaphragmatic muscle fibers, and that patients with severe COPD manifest increases in the percentage of type I fibers, impairment in the contractile function of diaphragmatic muscle, increase in protein degradation, and reduction in Ca2+ sensitivity and periodic locomotion of cross-bridges. Chronic electric stimulation using physiologic frequency may recruit motor units of atrophic diaphragmatic muscle, enhance the function of various types of muscle fibers, and maintain relatively normal percentages of various types of muscle fibers. Hence, physiologic frequency electric stimulation...