Figure 2. Sensory LTF in ex vivo CBs from naïve rats depends on stimulus pattern and strength.

Average integrated CSN activity in response to: (A) no gaseous challenge (control; open circles) or AIH‐Hc (red arrows; closed circles); (B) 10 bouts of hypoxia ($P_{{\mathrm{O}}_2}$ = 60 Torr; blue arrows) with concurrent sustained Hc (SHc) ($P_{\mathrm{C}{\mathrm{O}}_2}$ = 50 Torr; blue horizontal bar); (C) 10 bouts of hypoxia ($P_{{\mathrm{O}}_2}$ = 40 Torr; green arrows); (D) 10 bouts of Hc ($P_{\mathrm{C}{\mathrm{O}}_2}$ = 60 Torr; orange arrows); and (E) 10 min of acute continuous hypoxia‐hypercapnia (ACH‐Hc) ($P_{{\mathrm{O}}_2}$ = 40 Torr & $P_{\mathrm{C}{\mathrm{O}}_2}$ = 60 Torr; grey bar). F, summary of CSN activity 60 min after the last stimuli. Note that concurrent hypercapnia, which enhances the acute response of the CB to hypoxia, was necessary to induce sensory LTF. ^* P < 0.05 compared to baseline (dashed line) (one‐way ANOVA). All data are the mean ± SEM (n = 6 per group). rc, recirculated effluent; wrc, without recirculated effluent.