Novel NAD(P)H Oxidase Inhibitor Suppresses Angioplasty-Induced Superoxide and Neointimal Hyperplasia of Rat Carotid Artery

Neointimal proliferation occurring after vascular or endovascular procedures is a major complication leading to end-organ or limb ischemia. In experimental models, balloon injury has been shown to induce NAD(P)H oxidase to produce vascular superoxide anion (O2*-) production, which has been implicated in cell proliferation, but a direct link is still unclear. We postulated that inhibition of arterial NAD(P)H oxidase, resulting in decreased O2*-, would lessen the neointimal hyperplasia caused by balloon injury to the common carotid artery (CCA). Sprague-Dawley rats were implanted with osmotic minipumps containing either vehicle, a cell-permeant peptide that inhibits NAD(P)H oxidase (gp91ds-tat, 10 mg/kg per day), or a scrambled peptide control (scrmb-tat). Two days after pump implantation, the left CCA was injured using an intravascular balloon embolectomy catheter (2F Fogarty). Systolic blood pressure was monitored by tail cuff. Fourteen days after injury, CCAs were harvested and analyzed by digital morphometry. Rats in both groups remained normotensive, with no significant differences in systolic blood pressure. Reactive oxygen species measurements after injury indicated a significant reduction in vascular O2*- in rats infused with gp91ds-tat, and the neointima/media area and thickness ratios were significantly lower in their arteries compared with control. On the contrary, no significant change in overall CCA diameter was observed in any group. Our data indicate that in response to balloon injury of the rat carotid artery, NAD(P)H oxidase activity contributes to neointimal hyperplasia and is involved in vascular cell proliferation and migration during restenosis.