ADENOSINE PROTECTS AGAINST ATTENUATION OF FLOW RESERVE AND MYOCARDIAL-FUNCTION AFTER CORONARY-OCCLUSION AND REPERFUSION

Total coronary artery occlusion and reperfusion result in attenuation of coronary blood flow reserve, regional myocardial dysfunction, and m yocardial leukocyte infiltration. To examine the effects of intracoron ary adenosine on these occlusion and reperfusion-induced perturbations , we subjected 14 dogs to total left anterior descending (LAD) coronar y artery occlusion (1 hour) and reperfusion (1 hour). Seven dogs recei ved adenosine (3.75 mg/min into the LAD distal to the occlusion) over a 1-hour period starting 5 minutes before reperfusion, and the remaini ng seven dogs received saline solution. One dog in each group died of ventricular fibrillation during coronary artery occlusion. Coronary fl ow reserve, measured as peak reactive hyperemia (10 and 20 seconds of total coronary artery occlusion) and peak coronary blood flow response to acetylcholine (0.01 to 1.0 mu g) and nitroglycerin (5 to 25 mu g), was impaired in the LAD region after LAD occlusion and reperfusion in the saline-treated dogs (all p < 0.01 vs before occlusion and reperfu sion); LAD regional myocardial shortening fraction measured by ultraso nic crystals was also diminished after occlusion and reperfusion in sa line-treated dogs (-5% +/- 1% vs 12% +/- 2%; p < 0.02). The adenosine- treated dogs showed total protection against toss of coronary flow res erve (peak reactive hyperemia and blood flow increase in response to a cety(choline and nitroglycerin; all p values not significant vs before LAD occlusion and reperfusion). LAD regional myocardial shortening fr action was also preserved in adenosine-treated dogs (9% +/- 2% vs 14% +/- 2%; p not significant). Myocardial myeloperoxidase activity, measu red as an index of myocardial leukocyte infiltration, was greater (p < 0.02) in the LAD ischemic-reperfused regions than in nonischemic circ umflex regions in the saline-treated dogs. A similar difference in mye loperoxidase activities in the reperfused and control regions was not observed in the adenosine-treated dogs. Thus adenosine protects agains t loss of coronary flow reserve and regional myocardial function in do gs subjected to coronary artery occlusion and reperfusion.