Coronary vasodilation by nitrates is not mediated by the prostaglandin system: A quantitative cineangiographic study

The possible role of prostaglandins in mediating large coronary artery vasodilation by nitrates was investigated by quantitative magnification coronary angiography. The effects of aspirin (1 g systemically and 100 mg intracor-onary) in preventing large coronary artery vasodilation induced by intracoronary isosorbide dinitrate was investigated in 16 patients. Of these, 5 received 0.3 mg (Group 1A) and 11 received 3 mg (Group 1B) intracoronary isosorbide dinitrate, before and 15 minutes after aspirin. Relative to control, 0.3 mg isosorbide dinitrate induced a 19 ± 9% (mean ± SD) (p Changes after 3 mg isosorbide were 23 ± 12% (p Urinary 6-ketoprostaglandin-F1α values in urine samples collected in the 8 hours before and the 8 hours after the study in five patients in Group 1B and five patients of Group 2, revealed a 36 ± 14% (mean ± SD) reduction in excretion of prostacyclin (p