Effect of 7-oxo-PGI2 on myocardial infarct size and role of oxygen radicals in its protective effect.

The ability of the prostacyclin analogue 7-oxo-PGI2 to inhibit infarct size in in vivo rat heart was assessed. Anaesthetized rats were subjected to coronary artery ligation for 72 hours and infarct size was measured macroscopically using staining with triphenyl tetrazolium chloride. Systolic blood pressure and electrocardiogram were monitored. 7-oxo-PGI2 (50 micrograms/kg, i.p.), administered 30 minutes before or after coronary artery ligation, markedly reduced infarct size and loss of R wave. It did not, however, influence the changes of systolic blood pressure and heart rate in these animals. In addition, 7-oxo-PGI2, both in vitro and in vivo, inhibited rat PMN-evoked and luminol-enhanced chemiluminescence and markedly reduced the increase in serum malonyldialdehyde levels occurring after coronary artery ligation. The capacity of 7-oxo-PGI2 to impair the generation of oxygen free radicals from PMN cells, which reach the site of ischaemic injury through the limited collateral flow available in rat myocardium, may be responsible for its beneficial effect on ischaemic myocardial injury.