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Role of cyclooxygenase-2 in myocardial infarction and ischaemia.

OBJECTIVE
To determine the role of cyclooxygenase-2 (COX-2), on coronary perfusion rate (CPR) in a rabbit heart model showing ischaemic damage and reperfusion injury to the myocardium.


DESIGN
An experimental study.


PLACE AND DURATION OF STUDY
The animal unit of the Dr. Panjwani Center for Molecular Medicine and Drug Research, ICCS, University of Karachi during July 2004 to June 2005.


MATERIALS AND METHODS
Rabbits were divided into three groups of six animals each. Group I had normal rabbits, group II consisted of infarcted rabbits (infarction induced by 65 mg /kg isoproterenol (ISP) and group III consisted of infarcted rabbits that received nimesulide, a COX-2 inhibitor (25 mg/kg). MI was induced in rabbits by ISP, a beta-agonist drug given by the intraperitoneal route. In this model, the acute phases of myocardial necrosis and repair mimicked those which occurred in humans. Induction of MI was confirmed by measuring changes in serum creatinine phosphokinase (CPK) and troponin I (TPI) levels, electrophysiological (ECG) changes and histochemical changes in the left ventricle before and after ISP injection. Coronary perfusion rate (CPR) was monitored using Langendorff isolated heart preparation at day 2, 4, 8 and 16 of post-infarction.


RESULTS
CPR of infarcted and nimesulide treated rabbits displayed significant improvement on each corresponding day post-infarction as compared to the infarcted and control rabbits (p <0.01).


CONCLUSION
Using this model, it was found that nimesulide, a COX-2 inhibitor, exerted a cardioprotective effects in MI.