Arteriogenesis and ischemia impair functional vasodilation in resistance arteries

Abstract

Collateral-dependent hyperemia is reduced following arterial occlusion, but the role of impaired vasodilation in this reduction is unknown. Additionally, ischemia impairs arteriolar vasodilation, but its impact on resistance artery vasodilation is unknown. To examine the impact of arteriogenesis and ischemia on resistance artery vasodilation, we ligated or resected the femoral artery, respectively. Arteriogenesis transiently impairs functional vasodilation, which is reduced at day-7, but improves by day-14. We hypothesize that the presence of synthetic smooth muscle cells underlies this impairment; studies are underway to examine smooth muscle cell phenotype during arteriogenesis. Ischemia also impairs functional vasodilation by making resistance arteries less sensitive to vasodilation stimuli- vasodilation occurs in response to 500μs pulse durations, but not 200μs at day-14. This impairment seems to be exacerbated with age. Although the dynamic range of acetylcholine-mediated vasodilation is reduced in ischemic arteries, the maximum diameter is not different from control. Studies are underway to determine if ischemic arteries have undergone arteriogenesis or are dilated at rest due to tissue hypoxia.