Ischemic preconditioning translocates PKC-δ and -ε, which mediate functional protection in isolated rat heart

Protein kinase C (PKC) plays an important role in mediating ischemic preconditioning (PC). However, the relationship between PKC isoforms and PC is still uncertain. We analyzed subcellular localization of PKC isoforms by Western blot analysis in isolated rat heart and demonstrate that PKC-alpha, -delta, and -epsilon were translocated to the membrane fraction associated with the improvement of cardiac function. Translocation of PKC-delta and -epsilon persisted after a 30-min period following PC, but the translocation of PKC-alpha was transient. Under low Ca2+ perfusion (0.2 mmol/l), PC improved the cardiac function associated with the translocation of PKC-delta. Chelerythrine (1.0 micromol/l) suppressed the translocation of all PKC isoforms associated with the loss of improvement of the cardiac function. On the other hand, bisindolylmaleimide (0.1 micromol/l) did not inhibit the improvement of cardiac function induced by PC, which was associated with the translocation of PKC-epsilon. These results indicate that the effect of PC on cardiac function is mediated by the translocation of either PKC-delta or -epsilon independently in rat hearts.