INITIAL REPERFUSION WITH 2,3-BUTANEDIONE MONOXIME IS BETTER THAN HYPERKALEMIC REPERFUSION AFTER CARDIOPLEGIC ARREST IN ISOLATED GUINEA-PIG HEARTS

Objective. Initial warm cardioplegic reperfusion is widely used to ame liorate cardiac reperfusion damage after cardioplegic arrest. However, undesired effects of the high potassium concentration of the cardiopl egic perfusate may limit the beneficial effect of this treatment. Cont raction uncoupling by a negative inotropic and vasodilating agent such as 2,3-butanedione monoxime (BDM) may be superior to warm cardioplegi c reperfusion in reducing reperfusion damage. Thus, initial reperfusio n with BDM was compared with hyperkalemic reperfusion (HKR) after glob al ischemia of Langendorff-perfused guinea pig hearts. Methods, Cardia c arrest was induced in 16 hearts using hyperkalemic Krebs' solution a nd hearts were stored unperfused at 37 degrees C for 40 min, Two group s were studied: HKR, initial reperfusion with 37 degrees C oxygenated hyperkalemic Krebs' for 5 min, and BDM, addition of 20 mM BDM to normo kalemic Krebs' for 5 min. Results. BDM increased reactive coronary ref low (128+/-8%; all data mean+/-SEM of baseline) much more than HKR tre atment (65+/-5%). O-2 consumption was reduced more by HKR (28+/-1%) th an by BDM (42+/-4%), but the O-2 supply/consumption ratio was higher w ith BDM. During perfusion with normal Krebs' solution, flow stabilized at about 75% of baseline in both groups. Post-ischemic responses to a denosine, serotonin, and nitroprusside were depressed to a similar deg ree in both two groups. Recovery of left ventricular developed pressur e was better in BDM (69+/-2%) than in HKR (61+/-3%)-treated hearts. Re perfusion dysrhythmias were markedly reduced after BDM reperfusion. Co nclusions. These data indicate that treatment in the initial 5-min rep erfusion period with BDM. is more effective than hyperkalemic reperfus ion in reducing reperfusion damage.