EFFECT OF SODIUM-NITROPRUSSIDE AND L-ARGININE METHYL-ESTER ON RAT HEARTS STORED AT 4 DEGREES-C FOR 24 H

1. This study examined the effects of altering nitric oxide levels wit h sodium nitroprusside or L-arginine in rat hearts stored hypothermica lly. 2. Hearts were microperfused at 4 degrees C for 24 h with a modif ied Krebs-Henseleit buffer (KHB) that contained either sodium nitropru sside, L-arginine, L-arginine methyl ester or dexamethasone. 3. After hypothermic storage, hearts were rewarmed to 37 degrees C with KHB alo ne or KHB containing sodium nitroprusside or L-arginine. Cardiac funct ion was then assessed in either Langendorff mode or working heart mode . 4. Compared with values from fresh unstored hearts. hypothermic stor ed hearts showed a significant decrease in coronary flow and left vent ricular developed pressure when the stored hearts were perfused in Lan gendorff mode. These hearts also produced less aortic flow and cardiac output when perfused in the working mode. 5. Hearts hypothermically m icroperfused with buffer containing either L-arginine or sodium nitrop russide and then reperfused in the Langendorff mode with untreated KHB buffer had the highest left ventricular developed pressure and corona ry flow values. Aortic flow and cardiac output were also higher in the se hearts. 6. In all groups of stored hearts, the concentrations of bo th ATP and creatine phosphate were significantly low, when compared wi th values from freshly isolated hearts. Addition of dexamethasone to t he buffer either during storage or during reperfusion had no beneficia l effect on high-energy phosphate loss or cardiac performance of store d hearts. 7. This study showed that the addition of nitric oxide donor s to storage buffer significantly improves cardiac function on normoth ermic reperfusion. The improved functional recovery is unrelated to th e high-energy phosphate content of these hearts.