Ulinastatin has anti-inflammatory properties and protects organs from ischemia/reperfusion-induced injury. The aim of this study was to investigate whether ulinastatin provides a protective effect on a regional myocardial ischemia/reperfusion injury in an in vivo rat heart model and to determine whether the anti-inflammatory response is related to its myocardial protective effect.

Rats were randomized to two groups. One group is received ulinastatin (50,000 U/kg or 100,000 U/kg) diluted in normal saline and the other group is received normal saline, which was administered intraperitoneally 30 min before the ischemic insult. Reperfusion after 30 min of ischemia of the left coronary artery territory was applied. Hemodynamic measurements were recorded serially during 6 h after reperfusion. After the 6 h reperfusion, myocardial infarct size, cardiac enzymes, myeloperoxidase activity, and inflammatory cytokine levels were compared between the ulinastatin treated and untreated groups.

Ulinastatin improved cardiac function and reduced infarct size after regional ischemia/reperfusion injury. Ulinastatin significantly attenuated tumor necrosis factor-α expression and reduced myeloperoxidase activity.

Ulinastatin showed a myocardial protective effect after regional ischemia/reperfusion injury in an in vivo rat heart model. This protective effect of ulinastatin might be related in part to ulinastatin's ability to inhibit myeloperoxidase activity and decrease expression of tumor necrosis factor-α.