The KATP blocker sodium 5-hydroxydecanoate does not abolish preconditioning in isolated rat hearts

Blockers of ATP-sensitive K+ channels (KATP) abolish preconditioning in several species. Glyburide does not abolish preconditioning in rat hearts, but this may be due to a loss of its activity during ischemia. We determined the effect of a KATP blocker, which is more active during ischemia (sodium 5-hydroxydecanoate, 5-HD), on preconditioning in isolated rat hearts. Rat hearts were subjected to 4 periods of 5 min global ischemia followed by 30 min of global ischemia and reperfusion. Preconditioning significantly enhanced post-ischemic recovery of function and reduced lactate dehydrogenase (LDH) release vs. sham. 5-HD (100 microM) did not abolish preconditioning. Cromakalim (20 microM) was protective in this ischemic model and this was abolished by 5-HD. This is further evidence that KATP opening is not the mechanism of preconditioning in rats.