CO2 inhalation reduces amygdala pH. (A) Examples of pH recordings in amygdala showing effects of CO2 inhalation. (B) Mean pH response in basolateral amygdala to CO2 inhalation was normal in ASIC1a−/− mice. ANOVA revealed a significant effect of CO2 (F (2, 15) = 7.8, p < 0.01), but no effect of genotype (F(1, 15) = 0.2, p = 0.66) and no interaction (F< 1, n = 3–4 mice per group). (C) Lateral ventricle pH response to CO2 inhalation. ANOVA revealed a significant effect of CO2 (F (2, 30) = 12.0, p < 0.001), but no effect of genotype (F(1, 30) = 1.2, p = 0.3) and no interaction (F< 1, n = 6 mice per group).