Cardioprotective effects of melatonin on recovery of rat donor hearts after 12-hour preservation.

The cardioprotective effects of melatonin on recovery of rat donor hearts after 12 h of preservation were investigated. Wistar rats weighing 200 to 250 g (n=24) were randomly divided into 3 groups. In the non-storage group (n=8), donor hearts were not stored. In the melatonin group (n=8), donor hearts were stored in 4 degrees C St. Thomas solution with melatonin (0.1 mmol/L). In the control group (n=8), donor hearts were stored in 4 degrees C St. Thomas solution only. The coronary flow (CF), cardiac function, coronary vasodilatory response, creatine kinase (CK) and high energy phosphate levels were measured after the hearts had been preserved for 12 h. Transmission electron microscopy was used to examine the microstructural changes after 12 h of preservation. The recovery of cardiac function and coronary vasodilatory response were significantly improved in the melatonin group (P<0.01). CK release decreased greatly in the melatonin group (P<0.01). High energy phosphate levels were significantly better preserved in the melatonin group (P<0.01). Histological findings were much better in the melatonin group than in the control group. These results suggest that melatonin has cardioprotective effects on the recovery of rat donor hearts after 12 h of preservation.