Fig. 1. Effects of hypoxia on action potential duration at 50% (APD₅₀) and 90% (APD₉₀) of full repolarization (N=8). Action potentials recorded in isolated ventricles were significantly shortened after 10 min hypoxia (6.1±0.2 kPa), an effect that was reversible upon a return to normoxic solution (washout). Inset shows representative action potential configuration in one experiment. Values are means ± 1 S.E.M. ^*, significantly different from values recorded under normoxic conditions (P<0.05).