Figure 6.

CO₂ sensitivity of Phox2b-expressing neurons. A–C, Immunofluorescence images showing expression of cFos and mCherry. The mouse was exposed to 8% CO₂ for 50 min before immunohistological experiments. CO₂-activated neurons were denoted by the immunoreactivity for cFos (green, A). The cFos⁺mCherry⁺ neurons (denoted by arrows, C) represented CO₂-activated transduced neurons. Scale bar, 25 μm. D, Rostrocaudal distribution of cFos⁺mCherry⁺ neurons in 6 coronary sections from each mouse exposed to different concentrations of CO₂. Number of mice: n = 8 for 100% O₂; n = 6 for 5% CO₂; n = 5 for 8% CO₂. E, Comparisons in the average number of cFos⁺mCherry⁺ neurons of each group based on cell counts in D. F, Proportion of cFos⁺mCherry⁺ neurons in the total number of mCherry⁺ or cFos⁺ neurons. The calculations were made based on cell counts in E. ***p < 0.001 (one-way ANOVA with Tukey's test). ****p < 0.0001 (one-way ANOVA with Tukey's test).