Figure 2

Nicotine evoked currents in acutely dissociated DRG neurons. Nicotine was applied for 500 ms to neurons held at −60 mV via a fast application system. A. Two types of currents were detected in mouse DRG neurons that were distinguishable based on differences in activation and inactivation kinetics: A fast current (left) that activated and inactivated rapidly and a slow current (right) that activated and inactivated more slowly. B. Fast (top traces) and slow (bottom traces) currents were activated by nicotine over a comparable concentration range. Fast and slow currents were evoked from the same neuron in response to increasing concentrations of nicotine. A third even more slowly activating current (top trace, right side) was evoked at higher (1000 μM) concentrations of nicotine and was present in most neurons with fast current as well as a significant number of neurons without either fast or slow current. C. Concentration response data from individual neurons with fast (n = 26) or slow (n = 16) current were pooled and fitted with a Hill equation to estimate the maximal evoked current and the concentration at which a current 50% of maximal was evoked (EC50).