After 20min electric field stimulation,L-enkephalin (L-ENK) content in the rabbitear artery declined from the control value of 38.99±17.29 to 12.55±1.96
mouth occlusion pressure (P<sub>0.1</sub>) rather than inspiratory ventilation (V<sub>1</sub>)and mean inspiratory airflow ((?)) was used for expounding the mechanism