Fig. 2.

RTN injection of fluorocitrate (FCt) increases respiratory activity. A and B: recordings of end-expiratory CO₂ (etCO₂), arterial pressure (AP), and integrated phrenic nerve activity (iPNA) in urethane-anesthetized and artificially ventilated rats show that injection of FCt (1 mM, 50 nl) into the RTN increased breathing in 2 experimental conditions, i.e., below (etCO₂: 3–4%; A) and above the PNA threshold (etCO₂: 6–7%; B). C and D: summary data show changes in PNA amplitude (ΔPNA amplitude; C) and PNA frequency (ΔPNA frequency; D) produced by unilateral injections of saline or FCt into the RTN in a condition of 6–7% etCO₂. *Different from saline (n = 6/group).