| Diaphragm pacing( DP) by electrical stimulation of the phrenic nerve is an established mode of ventilation for patients with high cervical cord lesions or central hypoventilation syndrome. In recent years, DP has been developed to become one standard assisting technology of ventilation function in some foreign medical centers. The integrity of thorax, lung, phrenic nerve and diaphragm is the basic requirement of diaphragm pacing, or the phrenic nerve is repaired by intercostal nerve grafting after injury. The function and structure of respiratory muscles will be brought about denervation changes after phrenic nerve injury. It is not very clear of the pacing time and the ventilation function or the changes in respiratory muscle after that. We supposed to observe the ventilation function, the protein and energy metabolism of respiratory muscle and the changes of electromyogram hi animal mode of unilateral phrenicotomy to find out the regularity .Objective: Animal mode of canines with unilateral phrenicotomy were established to study the changes of ventilation function, adenine nucleotide and protein, ultrastructure of respiratory muscles and to explore the changes of electromyogram of diaphragm after electrical stimulation. The theoretical basis is expected to produce for the patients with phrenic nerve damage but who still need diaphragm pacing for ventilation support.Methods: 1. 8 healthy adult hybrid canines were experimented when the phrenicnerves were intact(A group), 1 month after unilateral phrenicotomy, 4 canines were drawed out randomly as 1 month group(B group) and the other 4 canines were 2 month group(C group) which would be tested 2 month later after phrenicotomy. The 8 canines were generally anaesthesized with thiopental sodium(15mg/kg), then intubated endotracheal tube and fixed in the operation table in right lateral decubitus position. The ventilation function(Tidal volume and Minute ventilation volume) of canines were measured by Datex pulmonary function monitoring equipment before thoracotomy. The ventilator was used to keep ventilation. After thoracotomy, the diaphragmatic and intercostal muscles were cut and put into glutaral and liquid nitrogen for preservation. The left phrenic nerves were exposed and the recording electrodes of diaphragmatic EMG , leads, and the electrode of diaphragm pacemaker were placed . The EMGs were recorded when the phrenic nerves were intact. Then the phrenic nerves were cut off, the diaphragms were stimulated by the diaphragm pacemaker, the EMGs were recorded. After the surgery, the canines recovered self-breath, the ventilation functions were recorded again. After the experiment, the canines were sent to the doghouse and feed. The experiments were repeated after one and two months later. 2. Compare the ventilation functions among A ,B and C team. 3. Determine the changes of the protein in the respiratory muscles. 4. Determine the changes of the adenine nucleotide in the respiratory muscles. 5. Observe the changes of the ultrastructure of respiratory muscles by electron microscope. 6. Compare the EMGs among A ,B and C group. 7. The experimental datas were analysed by using the software packages of SPSS 11.0.Results: 1. The changes of ventilation function: The tidal volumes were decreased after phrenicotomy and increased one month later; The tidal volume was the lowest right after the phrenic nerve was cut off, comparing to the canines whentheir phrenic nerves were intact, P<0.05; 1 month after phrenicotomy, the tidal volume was almost got back. The minute ventilation volumes had no statistically difference between the groups after and before phrenicotomy. 2. The changes of the content of protein in the respiratory muscles. The contents of protein in diaphragms were decreased continually after phrenicotomy, but there were no statistically difference between the groups A, B and C. The contents of protein in intercoastal muscles were uptrend postphrenicotomy, The contents of protein of C group were significantly higher than that of A group(P<0.05). 3. T...
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