Aging affects vascular structure and function in a limb-specific manner

Abstract

The limb-specific effects of aging upon vessel structure and function are not well understood. Consequently, in 12 young (26 ± 2 yr) and 12 old (72 ± 1 yr) healthy subjects, we utilized ultrasound Doppler to evaluate intima-media thickness (IMT), ischemic reperfusion, and flow-mediated dilation (FMD) following (5 min) suprasystolic cuff occlusion in both the arm [brachial artery (BA)] and the leg [popliteal artery (PA)]. Structural measurements, whether normalized for vessel size or not, revealed a greater IMT in both the BA and PA with age (young: BA 0.028 ± 0.001 and PA 0.046 ± 0.003 cm, old: BA 0.039 ± 0.002 and PA 0.073 ± 0.005 cm; P < 0.05). Ischemic reperfusion revealed a similar pattern as IMT in terms of limb and age-related differences. There was an age-related attenuation in both BA FMD (old: 38% smaller BA FMD compared with young) and PA FMD (old: 71% smaller PA FMD compared with young). However, when this percent change was normalized for shear rate, only the PA FMD of the old group was still significantly attenuated (old: 41% smaller PA FMD/shear rate compared with young). Together, the finding of differential structural and functional parameters in the arms and legs of healthy young people, and the somewhat negative findings that are specific to the legs of otherwise healthy older people (greater IMT and attenuated FMD), support and may help to better understand the increased propensity to develop a vascular pathology in the legs with age.