Effects of 7-hydroxycoumarin (umbelliferone) on isolated perfused and ischemic-reperfused rat heart

7-Hydroxycoumarin (CAS 93-35-6, 7-HC) is the main coumarin (1,2-benzopyrone) metabolite and the therapeutic active molecule. It exhibits antioxidant properties in vitro and may share with other coumarin derivatives vasodilator effects. The aim of the study was to assess the effects of 7-HC on isolated perfused and ischemic-reperfused rat heart. After a 10-min perfusion, an increase in the coronary flow was observed with 7-HC at 10(-4) mol/l (p = 0.002) as well as an increase in left ventricular developed pressure with 7-HC at 10(-5) mol/l (p = 0.038). The increase in coronary flow is not solely explained by the increase in inotropism. It appears to be also induced through a direct vasodilator effect which, however, does not involve the release of vasodilator prostaglandins since it was not inhibited by indometacin. After the 30-min global ischemia and the 45-min reperfusion period, 7-HC at 10(-5) mol/l induced an increase in left ventricular developed pressure (p = 0.042) and in the ratio of heart rate x left ventricular developed pressure over oxygen consumption (p = 0.036).