Vasoconstrictor prostanoids may be involved in reduced coronary reactive hyperemia after ischemia–reperfusion in anesthetized goats

Abstract

To examine coronary vasodilator reserve after ischemia–reperfusion, reactive hyperemia was determined during reperfusion after partial and total, brief and prolonged ischemia. To this, left circumflex coronary artery flow was electromagnetically measured, and partial (60 min) or total (15 and 60 min) occlusions of this artery were induced, followed in each case by 60-min reperfusion in anesthetized goats untreated and treated with N W-nitro- l-arginine methyl ester ( l-NAME) or meclofenamate. In untreated and treated animals, coronary flow was decreased during reperfusion after the three types of ischemia. In hyperemic responses to 5- and 10-s coronary occlusions, repayment of debt decreased during reperfusion after the three types of ischemia in untreated animals, and this decrease was not affected by l-NAME. This decrease during reperfusion after partial and total, 60-min ischemia, but not after total, 15-min ischemia, reversed with meclofenamate. Peak hyperemic flow/control flow ratio decreased only during reperfusion after total 60-min occlusion in untreated animals and it was normalized by meclofenamate. These results show that ischemia–reperfusion reduces hyperemic response (vasodilator reserve); this diminution being dependent on duration and severity of ischemia. The hyperemic responses reduction during reperfusion after prolonged ischemia, but not after brief ischemia may be related at least in part to increased production of vasoconstrictor prostanoids.