CO2 inhalation increases arterial CO2 partial pressure (PaCO2) and stimulates ventilation normally in the ASIC1a−/− mice. (A) PaCO2 did not differ between ASIC1a+/+ and ASIC1a−/− mice. ANOVA revealed significant main effect of CO2 (F(1,8) = 50.2, p < 0.001; n = 3 per group), but not genotype (F < 1) and no interaction (F < 1). (B) CO2-evoked increases in minute ventilation relative to baseline did not differ between ASIC1a+/+ and ASIC1a−/− mice (F(1, 46) = 0.065, p = 0.80, ANOVA; from left to right groups comprised of 17, 17, 12, and 4 mice).