Spirapril and Cilazapril Inhibit Neointimal Lesion Development but Cause no Detectable Inhibition of Lumen Narrowing After Carotid Artery Balloon Catheter Injury in the Rat

Five groups of 12 rats were subject to balloon lesion of the left carotid artery and neointimal thickening was measured histologically 2 weeks after injury. Rat groups received either spirapril (3, 10 or 30 mg/kg/day, administered throughout the study in the food), cilazapril (10 mg/kg/day) or placebo. Spirapril caused a dose-dependent inhibition of the neointimal thickening of the rat carotid artery. The degree of inhibition with 10 mg/kg/d spirapril and cilazapril was similar (-44% and -42% respectively). The carotid lumen area was measured in vivo by nuclear magnetic resonance (NMR) imaging both before and 2 weeks after balloon injury and also postmortem by histological techniques. Two weeks after injury, the lumen area of the left carotid artery was significantly reduced following balloon injury, as measured by both techniques. Treatment did not detectably modify this stenosis process despite the use of two independent methods for assessing lumen size, even though neointimal thickening was strongly at...