Fig. 3.

Ventilation was disrupted at distinct postnatal ages in DA^Tph2−/− rats. A: representative plethysmographic recordings of basal ventilation (measured as voltage deflections) in 1 WT (WT 125; blue) and a DA^Tph2−/− littermate (DA^Tph2−/− 127; green) rat at P1, P3, and P12 while breathing room air. Note that ventilation in the DA^Tph2−/− rat alternated between regular and highly irregular with apneas and large, atypical breaths compared with the WT, but that there was improvement by P3. However, by P12 ventilation was reduced and irregular in the DA^Tph2−/− rat. B: Poincare plots comparing the inter-breath interval (IBI) among consecutive breaths during room air exposure of WT (n = 9; 5,425 breaths) and DA^Tph2−/− (n = 9; 3,594 breaths) rats from P1-2. C: variability in the IBI was calculated by distance from the line of identity (“width” from LOI) or distance from the mean IBI along the LOI (“length”; see results), and averaged for each genotype and age. Note that variability in the IBI was significantly greater (P < 0.003) in DA^Tph2−/− rats at P1-2 and P11-12 but not at other ages tested (two-way ANOVA).