Effect of ketamine on nicotine-induced current in rat superior cervical ganglion neurons

Objective To investigate the effect of ketamine on nicotine-induced current in rat superior cervical ganglion neurons.Methods Newborn Wistar rats were used in this study.Neurons were isolated enzymatically from superior cervical ganglia of newborn rats in an aseptic condition and cultured in 90％ DMEM/F12,10％ horse serum containing penicillin 100 μg/ml for 5-7 d.Nicotine-induced current was measured and recorded using whole-cell patch clamp technique.A mixture of nicotine 50 μmol/L and different concentrations of ketamine ( 10,25,50,100 μmol/L) was added to the isolated neurons.The effect of ketamine on nicotine-induced current was evaluated.Results Nicotine-induced peak current was inhibited by ketamine in a concentration-dependent manner.The time constant of fast and slow desensitizing phase of the nicotine acetylcholine receptor was shortened after being exposed to the mixture of nicotine 50 μmol/L + 50 or 100 μmol/L ketamine as compared to nicotine 50 μmol/L-induced current.The median effective concentration of ketamine inhibiting nicotine-induced current was less than 20 μmol/L.Conclusion Ketamine can decrease nicotine-induced current in rat superior cervical ganglion neurons in a concentration-dependent manner indicating that inhibition of sympathetic activity is involved in the mechanism of decrease in BP by ketamine in specific condition. Key words: Ketamine;  Ganglia, sympathetic ;  Neurons;  Receptors, nicotinic