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Fig. 4. Effects of hypoxia (FIO2=fraction
of oxygen in the inspired air) on heart parameters before and after a 50%
reduction in haematocrit (filled and unfilled circles, respectively). (A,B)
Total cardiac output (
tot);
(C,D) heart rate (fH); (E,F) stroke volume (VS)
and (G,H) systemic blood pressure (1 cm H2O=98.1 Pa). 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. B, D, F and H show data for toads with
normal [O2] during normoxia, toads with normal [O2]
during hypoxia (FIO2=0.10), and
anaemic toads during normoxia. Significant differences between normoxic and
hypoxic animals are marked with `a', and differences between normoxic and
anaemic animals are marked with `b'. Data are presented as means ± 1
S.E.M. (N=6).