Fig. 1. Effects of hypoxia (F_IO2=fraction of oxygen in the inspired air) on arterial oxygen levels before and after reducing haematocrit (filled and unfilled circles, respectively). (A) Oxygen concentration ([O₂]); (B) haematocrit; (C) arterial oxygen tension (Pa_O2; 1 mm Hg=133.3 Pa); (D) haemoglobin concentration ([Hb₄]); (E) haemoglobin oxygen saturation (HbO₂sat) and (F) mean cellular haemoglobin concentration (MCHC). Significant effects of hypoxia within each of the two groups (normal and low haematocrit, respectively) are marked with an asterisk, and significant differences between the groups are marked with a dagger. Data are presented as means ± 1 S.E.M. (N=6).