THE K-ATP BLOCKER SODIUM 5-HYDROXYDECANOATE DOES NOT ABOLISH PRECONDITIONING IN ISOLATED RAT HEARTS

Blockers of ATP-sensitive K+ channels (K-ATP) 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 K-ATP blocker, which is more active dur ing ischemia (sodium 5-hydroxydecanoate, 5-HD), on preconditioning in isolated rat hearts. Rat hearts were subjected to 4 periods of 5 min g lobal ischemia followed by 30 min of global ischemia and reperfusion. Preconditioning significantly enhanced post-ischemic recovery of funct ion and reduced lactate dehydrogenase (LDH) release vs. sham. 5-HD (10 0 mu M) did not abolish preconditioning. Cromakalim (20 mu M) was prot ective in this ischemic model and this was abolished by 5-HD. This is further evidence that K-ATP opening is not the mechanism of preconditi oning in rats.