Evidence for superoxide radical-dependent coronary vasospasm after angioplasty in intact dogs.

BACKGROUNDActive oxygen species can influence vascular tone and platelet activation through a variety of mechanisms. This study assessed the role of the superoxide anion, the hydroxyl radical, and hydrogen peroxide in vasoconstriction and mural thrombosis after coronary artery angioplasty in intact dogs.METHODS AND RESULTSInjury was induced by inflation of a balloon catheter 50 +/- 6% above baseline arterial diameter; dogs were followed for 2 hours before death. Epicardial coronary diameters at arteriography and extent of thrombus deposition at serial histological sections were analyzed in controls (n = 20) and in dogs pretreated with superoxide dismutase (SOD, a superoxide radical scavenger, n = 10); other dogs were pretreated with the hydrogen peroxide scavenger catalase (n = 8), the iron chelator deferoxamine (n = 6), or the hydroxyl radical scavenger 1,3-dimethyl-2-thiourea (n = 9). Angioplasty-induced injury was similar among groups. After angioplasty, control dogs exhibited localized and persistent ...