Effects of intracoronary aspirin on coronary blood flow and reactive hyperemia were evaluated in closed- chest, anesthetized dogs. In 18 dogs the left circumflex coronary artery was cannulated and perfused by arte rial blood at a constant pressure. Coronary blood flow was measured by an electromagnetic flowmeter. In tracoronary aspirin at doses of 5, 10, and 20 mg reduced coronary blood flow in a dose-dependent manner. In jection of aspirin at doses of 10 to 25 mg also inhibited reactive hyperemia following the coronary occlusion for fifteen seconds. The mean peak flow ratio was reduced from 2.13 ± 0.42 to 1.75 ± 0.35 (p < 0.005). The incre ment of coronary blood flow provoked by intracoronary arachidonic acid at doses of 150 to 300 μg was almost entirely inhibited by the pretreatment of the coronary artery with aspirin.
The authors conclude that aspirin increases coronary arterial resistance in a dose-dependent manner and also restricts the maximal dilating capac ity, possibly by inhibition of pro stacyclin synthesis.
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