EFFECT OF INTRAVENOUS ADENOSINE ON MYOCARDIAL REPERFUSION INJURY IN A MODEL WITH LOW MYOCARDIAL COLLATERAL BLOOD-FLOW

The purpose of this study was to investigate the effects of various doses of adenosine administered intravenously on myocardial reperfusion injury in a model with poor collateral blood flow. New Zealand White rabbits were subjected to 30 minutes of occlusion of the obtuse marginal branch of the left circumflex artery and to 48 hours of reperfusion. Animals were randomized to receive intravenous adenosine in doses of 0.1 mg/min (low), 0.3 mg/min (intermediate), or 0.55 mg/min (high), or an equivalent volume of saline (control) commencing 5 minutes prior to reperfusion and continuing through the first 60 minutes of reperfusion. The area at risk was determined in vivo with Monastral blue dye and the area of necrosis was histologically examined with Masson's trichrome stain. Both the intermediate and high doses of adenosine, but not the low dose, significantly (p < 0.05) decreased mean blood pressure. However, all three doses of adenosine produced a significant (p < 0.05) and comparable decrease in infarct size expressed as a percent of area at risk (control, 52.0 +/- 4.6%; low, 35.3 +/- 4.1%; intermediate, 31.7 +/- 4.6%; high, 31.3 +/- 4.6%). Regional myocardial blood flow was significantly increased and coronary vascular resistance decreased by all three doses of adenosine in a subset of animals that did not undergo coronary occlusion (p < 0.05). This study demonstrates that intravenous administration of nonhypotensive doses of adenosine given during the early reperfusion period attenuates reperfusion injury in a model with poor collateral blood flow.