Fig. 2. Normoxic control mean arterial pressure (a) (A) and heart rate (B) for the three experimental groups: normoxia N21 (white bars), 15%O₂ H15 (grey bars) and 10%O₂ H10 (black bars). A dissimilar letter between incubation age groups indicates significant changes in a within an experimental group. ^*Significant difference between experimental groups at a given age; significant reduction in heart rate between incubation age groups within an experimental group. Values are means ± S.E.M. For N values, see Table 1.