The effect of adenosine on myocardial metabolism and oxygen consumption in the isolated dog heart preparation

The effects of adenosine on myocardial metabolism and oxygen consumption were examined in the isolated supported dog heart preparation (ISHP) perfused at a constant coronary blood flow. Heart rate was controlled by right atrial pacing. Coronary arterial and venous blood samples were collected and oxygen content, lactate, glucose and free fatty acid levels were determined. From arterialvenous differences and coronary blood flow, oxygen consumption and substrate uptake were determined. A 3 min intracoronary infusion of adenosine (50 and 100 μg/min) produced a significant dose-dependent decrease in MV?O₂ while increasing glucose uptake and decreasing the uptake of lactate. The decrease in oxygen consumption, the increase in glucose uptake and the decrease in the uptake of lactate were all found to be dependent on the initial MV?O₂. These findings suggest that, in addition to its putative role as a regulator of coronary vascular resistance, adenosine might also exert important metabolic effects on the heart.