Figure 2.

Second-hand tobacco smoke (SHS) exposure effects on endogenous substance P contribution to spiking response in rapid-onset spiking (RS) neurons. A. Typical spiking traces of RS neurons in the absence and presence of the NK₁ receptor antagonist (NK1R antag; SR140333, 3 µM) from both filtered air (FA)- and SHS-exposed animals. The antagonist slightly reduced the number of action potentials in response to 2 s depolarizing current injection in both FA- and SHS-exposed animals. B. The NK₁ receptor antagonist had a slight reduction in input resistance in both exposure groups. C. Group data confirmed that spiking response was significantly attenuated by NK₁ receptor antagonism in both FA (anova interaction, *P = 0.030) and SHS (anova interaction, *P < 0.001) exposure groups. D. NK₁ receptor sensitive spiking response to depolarizing current injection. The antagonist effects on spiking responses were similar in between FA and SHS exposure groups (anova interaction, P = 0.843), confirming no SHS exposure effect in RS neurons. aCSF, artificial cerebrospinal fluid.