Protective effects of electric stimulation of vagus nerve on acute lung injury in rat with sepsis

OBJECTIVE: To investigate the protective effect of stimulation of vagus nerve on acute lung injury in rat with sepsis. METHODS: Sepsis was reproduced by cecal ligation and puncture (CLP). Forty male Sprague-Dawley (SD) rats were randomly divided into 4 groups (each n=10): SHAM group received performed sham surgery. In CLP group, CLP was performed. In vagotomy (VGX) group, rats were subjected to bilateral cervical VGX following CLP. In vagus stimulation (STM) group, rats were subjected to bilateral cervical VGX after CLP and the efferent end of the left vagus nerve was stimulated with electric current. The animals were sacrificed at 18 hours after production. Tumor necrosis factor-alpha (TNF-alpha) level in blood was detected, arterial blood lactic acid concentration,pH, partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2), base excess (BE) and lung wet/drying (W/D) ratio were determined. The histopathology and ultra-microstructure of the lung were observed. RESULTS: The TNF-alpha and lactic acid concentrations, PaCO2 and W/D ratio were all increased, and pH, PaO2, BE all lowered in CLP group and VGX group compared with those of SHAM group (P<0.05 or P<0.01). Compared with CLP group, TNF-alpha, lactic acid concentration,PaCO2,W/D ratio in STM group were decreased obviously, and pH, PaO2 and BE were all increased (P<0.05 or P<0.01). The lung tissue pathology and ultra-microstructure changes indicated that lung injury was severe in CLP group than in SHAM group and was ameliorated in STM group compared with that of CLP group and VGX group. CONCLUSION: The results suggest that direct electrical stimulation of the efferent end of vagus nerve can protect lung against injury induced by sepsis in rat.