Fig. 2.

H₂O₂ biphasically affects the frequency of fictive normal inspiratory bursts. A: representative trace of the integrated population activity originating from the preBötC (∫preBötC) illustrating the biphasic effect that 2.2 mM H₂O₂ has on burst frequency of fictive inspiratory bursts. This biphasic effect was characterized initially by suppression followed by augmentation in burst frequency. Inset: expanded traces of single fictive normal inspiratory bursts taken during control (CON) or during H₂O₂ exposure (time bins 180, 300, and 600). B: effects of H₂O₂ on burst frequency; in a subset of experiments (n = 5) H₂O₂ was washed out and followed for an additional 600 s (gray bars) to demonstrate the reversibility of the effects of H₂O₂. C and D: irregularity score of f_inst [C; arbitrary units (A.U.)] and integrated burst area (D) were assessed by comparing average metric values (120-s bins) during control (CON) to those at 180, 300, and 600 s (black bars) during the 600-s exposure to H₂O₂ (n = 17 of 20 demonstrated a biphasic frequency response to H₂O₂; **P < 0.01). Washout bins were taken at 780, 900 and 1,200 s. ‡No significant differences were found between washout values and respective control values.