Effects of intracoronary infusion of adenosine on cumulative deterioration of regional myocardial wall motion induced by repeated brief periods of coronary occlusion in anesthetized dogs.

The present study was performed to evaluate the effects of the intracoronary infusion of adenosine on regional wall motion in the canine heart subjected to repeated brief coronary occlusion and reperfusion. In anesthetized open-chest dogs, six episodes of five-minute coronary occlusion followed by a fifteen-minute reperfusion were performed. Animals received infusions of either adenosine or saline (control) into the coronary artery during the initial five minutes of each reperfusion. Changes in regional wall motion were studied by means of ultrasonic crystals. The authors prolonged the duration of hyperemic flow at each reperfusion in a third group by means of a roller pump to examine whether the increase in coronary flow during reperfusion itself might affect the process of the deterioration of regional wall motion. In the control dogs, wall thickening decreased progressively after each reperfusion. However, in the adenosine-treated animals, regional wall motion fifteen minutes after the sixth reperfusion did not differ from baseline. Prolongation of hyperemic flow did not improve the progressive decline in regional wall motion. Thus, adenosine prevented the cumulative decrease in the regional wall motion of the myocardium treated with a series of repeated transient coronary occlusions, most likely by a mechanism unrelated to its vasodilating action.