BENEFICIAL-EFFECTS OF THE ATP-SENSITIVE K-FUNCTION FROM CARDIOPLEGIC ARREST IN ISOLATED-PERFUSED RAT HEARTS( CHANNEL OPENER CROMAKALIM ON RECOVERY OF CARDIAC)

We investigated the effects of cromakalim, an ATP sensitive (K-ATP(+)) channel opener, and glibenclamide, an K-ATP(+) channel blocker on car diac function when given before the cardioplegic arrest in isolated wo rking rat heart model. Hearts were subjected to normothermic (37 degre es C) ischemic arrest for 35 min with St. Thomas' Hospital cardioplegi c solution followed by reperfusion for 15 min and then again converted to working heart mode to assess the postischemic recovery rates of ao rtic flow (AoF), cardiac output (CO), stroke volume (SV), coronary flo w (CF) and heart rate (HR). Pretreatment with cromakalim (0.3, 1 mu M) given in the perfusion solution improved the recovery rates of AoF, C O, SV and CF from the control Values of 48.6+/-2.9%, 53.8+/-3.5%, 56.6 +/-4.9% and 74.6+/-3.2% to 86+/-3.8%, 90.4+/-2.5%, 92+/-1.7% and 102.2 +/-5.2%, respectively with 1 mu M of cromakalim. When glibenclamide (1 mu M) was added, the recovery rates of AoF and CO were only partially improved compared with the control group. The recovery rates of cardi ac function after the cromakalim treatment were, therefore, better tha n those with glibenclamide. These results indicate that the pretreatme nt with cromakalim in addition to ST. Thomas' Hospital cardioplegic so lution more effectively preserves the cardiac function after ischemia and reperfusion than that does glibenclamide in the rat heart.