Impaired endothelium-dependent vasodilation of coronary resistance vessels in severely stunned porcine myocardium

textabstractThe effect of stunning on endothelium-dependent responses of resistance vessels in vivo remains of interest. We utilized the coronary pressure-flow relationship during maximal vasodilation in anesthetized swine to identify subtle changes in flow reserve within stunned myocardium. Prior to and following stunning, the coronary pressure-flow relationship during maximal doses of intracoronary adenosine was compared with that of the endothelium-dependent vasodilator ATP. In 11 anesthetized swine, 30 min of partial LAD occlusion and 40 min of reperfusion reduced fractional shortening from 16±4% to 6±5% (p30 mmHg) was 1.31±0.54 ml/min-mmHg at baseline and 1.30±0.55 ml/min-mmHg following stunning (NS). With ATP however, the slope decreased from 1.34±0.48 ml/min-mmHg at baseline to 1.08±0.47 ml/min-mmHg following reperfusion (p