Indices Of Resistance Artery Function In Upper And Lower Limbs Are Related In Young Women

Abstract

Brachial artery flow-mediated dilation (FMD) has long been used to assess conduit artery (macrovascular) function. Additionally, the reactive hyperemic (RH) response following FMD cuff occlusion can function as an assessment of upper limb downstream resistance artery (microvascular) function. Passive leg movement (PLM) is a newer assessment of lower limb downstream resistance artery function that has been previously validated against the vasodilatory response to FMD (FMD%), but only in men. PURPOSE: Therefore, the purpose of this study was to compare lower limb resistance artery function, assessed by PLM, to upper limb conduit artery and resistance artery function, respectively assessed by FMD% and FMD RH, in healthy young women. We hypothesized that PLM would be positively related to both FMD% and FMD RH. METHODS: PLM and FMD were performed on 63 healthy premenopausal women (ages 18-35 years) during the early follicular phase of the menstrual cycle. Blood flow velocity and arterial diameter were assessed using Doppler ultrasound. Pearson correlation coefficients were used to evaluate associations between PLM and FMD%/RH. PLM indices included change in leg blood flow (∆LBF) and leg blood flow area under the curve (LBF AUC) and FMD RH indices included change in brachial artery blood flow (∆BABF) and brachial artery blood flow area under the curve (BABF AUC). RESULTS: ∆LBF was significantly positively related to ∆BABF (r = 0.32, P = 0.01). LBF AUC was significantly positively related to BABF AUC (r = 0.33, P = 0.01). However, contrary to our hypothesis, FMD% was not related to ∆LBF (r = 0.10, P = 0.45) or LBF AUC (r = 0.15, P = 0.23). CONCLUSIONS: PLM and FMD RH indices were positively related in young women, suggesting overlap of microvascular physiological responses in the upper and lower limbs. However, upper limb conduit artery function assessed by FMD% was not related to any PLM indices in these healthy young women, suggesting that they are capturing different aspects of vascular function and should not be used interchangeably. Supported, in part, by NIH grant P20 GM113125