Figure 1.

Experimental design. After isolation, ventricular myocytes were allowed to stabilize for 30 min before treatment. Myocytes were then subjected to either pharmacological preconditioning with 30 μM U₅₀ (UP) or metabolic inhibition/anoxia preconditioning (MI/AP) with 10 mM Na₂S₂O₄+10 mM 2-DOG in glucose-free Krebs for three 1-min cycles separated by three min superfusion with normal Krebs solution. A group of cells were incubated with saline in Krebs as vehicle-preconditioning control (VP). Another two groups of myocytes were subjected to UP or MI/AP in the presence of 5 μM nor-BNI, which was administered 5 min before and throughout the preconditioning period. These two groups were NBI-UP and NBI-MI/AP, respectively. Then the ventricular myocytes in all groups were subjected to MI/A with 10 mM Na₂S₂O₄+10 mM 2-DOG in glucose-free Krebs solution for 9 min followed by superfusion with normal Krebs solution for 10 min–reperfusion.