Beneficial effects of iloprost on acute myocardial ischemia in dogs.

The effects of intravenous administration of iloprost, a prostacyclin analogue, on myocardial energy metabolism and myocardial blood flow (MBF) were examined in anesthetized open-chest dogs subjected to 60 min of myocardial ischemia by coronary ligation. Iloprost administration at levels of 0.1 or 0.2 micrograms/kg/min was started 30 min before the commencement of ischemia and continued throughout the 90 min observation period. Since systolic aortic pressure in the iloprost 0.2 micrograms/kg/min group showed significantly lower values than that in the control group, whereas no clear effect was observed with the lower concentration (0.1 micrograms/kg/min), this latter group was further investigated. This 0.1 microgram/kg/min dose of iloprost lacked influence on MBF in both ischemic and nonischemic areas but did result in a significantly higher value for high energy phosphate contents in the ischemic myocardium. Moreover, myocardial mitochondrial respiratory function in the ischemic area was significantly improved. These results indicate that iloprost brought about preservation of myocardial energy metabolism without alteration of coronary perfusion, suggesting that it may exert a direct cardioprotective effect.