Single-unit carotid chemoafferent activity recorded under baseline conditions (21% O2/5% CO2) for (A) P4, (B) P7, and (C) P14 neonatal rats reared in 21% O2 (Control) or 60% O2 (Hyperoxia) from birth. Values are mean±SEM. Number of observations (Control, Hyperoxia): P4 (n=17, 20), P7 (n=16, 18), P14 (n=16, 11). * P<0.05 vs. Control within the same age group.