Effects of antiinflammatory drugs in a model of acute transmural infarction in the dog

The influence of several anti-inflammatory drugs, steroidal and nonsteroidal, on infarct size (quantification by epicardial electrocardiograms and expressed as percentage of left ventricular weight), coronary retrograde flow (measured by collection), frequency of infarction-arrhythmias (expressed as number of premature ventricular beats per min in the after-occlusion period) and hemodynamics, was examined on a model of acute transmural infarction in anesthetized open-chest dogs. Propranolol, used as a reference drug, produced a significant decrease of the infarct size. Indomethacin, (10 mg/kg i.v.) increased infarct size and ectopic rate and decreased retrograde flow while developing greater tachycardia and less hypotension than in controls. Acetylsalicylic acid (30 mg/kg i.v.) and meclofenamic acid (1 mg/kg i.v.) decreased infarct size without altering other parameters except for an increase in retrograde flow produced by acetylsalicylic acid. Ibuprofen (15 mg/kg i.v.) did not significantly affect any of the parameters considered in this study. Hydrocortisone (25 mg/kg i.v.) did not modify infarct size, collateral flow or hemodynamics but increased ectopic rate. These results emphasize the differential effects of anti-inflammatory drugs on acute myocardial infarction and suggest that mechanisms other than stabilization of myocardial lysosomes of inhibition of platelet aggregation may be involved, probably of direct, metabolic or cellular, nature.