Figure 1.

Fictive breathing activity recorded from brainstem slices in vitro. A, Consequences of five bouts of 3 min hypoxia separated by 3 min of reoxygenation, i.e., AIH. A1 shows the integrated activity recorded from the preBötC (top trace) and the O₂ level in the bath (bottom trace). Enlarged timescale of the fictive breathing activity before (A2) and after (A3) AIH. B, Same as A but in the presence of NE. B1 shows the integrated activity recorded from the preBötC (top trace) and the O₂ level in the bath (bottom trace). Enlarged timescale of the fictive breathing activity before (B2) and after (B3) AIH. C, Parameters of the fictive breathing activity observed before AIH and/or drug injection (baseline) and 30 min after the last bout of hypoxia (or 60 min after baseline). The inspiratory burst instantaneous frequency (C1) and amplitude (C3) as well as the IS of frequency (C2) and amplitude (C4) were measured (number of slices in each condition: n = 9 unperturbed; n = 8 NE; n = 15 AIH; n = 19 AIH + NE at 2 μm; n = 6 AIH+NE at 4 μm). Note the significant increase of burst frequency and IS of amplitude in slices exposed to AIH and NE. Also note the significant increase of IS of frequency in slices exposed to AIH and NE at 4 μm (two-way ANOVA followed by Holm–Sidak post hoc test; * represents significant difference compared with baseline in one group; $ represents significant difference between groups at the same time; different levels of statistical differences are not represented).