Fig. 3.

Selective ablation of retrotrapezoid nucleus (RTN) chemoreceptor neurons blunts the hypercapnic ventilatory response (HCVR). A: representative traces of ventilation during normoxia ($F{I}_{O_2}$ 21%), hypoxia ($F{I}_{O_2}$ 10%), and hypercapnia (${\text{F}\mathrm{I}}_{{\text{CO}}_{\text{2}}}$ 7%). B and C: respiratory frequency (ΔR_f) during hypoxia (B) and the hypoxic ventilatory response (HVR) (C) were not different between groups. D and E: the respiratory frequency (ΔR_f) during hypercapnia (D) and the hypercapnic ventilatory response (HCVR) (E) were increased in heart failure (HF) rats and substance P-conjugated saporin (SSP-SAP) toxin reduced both. Data represent mean ± SE (B, C), and box and whiskers represent median ± range (D, E). One-way ANOVA followed by Holm-Sidak post hoc test; n = 6 rats per group. *P < 0.05 vs. Sham+Veh; +P < 0.05 vs. HF+Veh. n.s., not significant.