Differential effects of aging on limb blood flow in humans

Donato, Anthony J.; Uberoi, Abbhimanyu; Wray, Walter; Nishiyama, Steven K.; Lawrenson, Lesley; Richardson, R. S.

doi:10.1152/ajpheart.00405.2005

Cited by 145 publications

(196 citation statements)

References 42 publications

(53 reference statements)

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“…Ten patients with COPD were enrolled based on spirometric evidence of moderate to severe airflow obstruction [FEV 1/FVC Յ 0.7 (10)], as assessed by standard pulmonary function tests performed during an initial visit to the laboratory. General anthropometric characteristics, including thigh volume, which was used to estimate quadriceps muscle mass (16), were also determined during this visit. Resting arterial blood analyses, collected in a parallel study in which the current subjects took part, are also presented here to better characterize the patients.…”

Section: Methodsmentioning

confidence: 99%

Ascorbate infusion increases skeletal muscle fatigue resistance in patients with chronic obstructive pulmonary disease

Rossman

Garten

Groot

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

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Section: Methodsmentioning

confidence: 99%

Ascorbate infusion increases skeletal muscle fatigue resistance in patients with chronic obstructive pulmonary disease

Rossman

Garten

Groot

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

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“…To illustrate, recent studies that assessed FMD in the arm and leg (5,19,33,34) have concluded that limb differences exist in FMD, possibly as a consequence of differences in activity level and/or arterial pressure. However, limb differences may, in part, also relate to baseline artery size, since arteries in the leg and arm differ in dimension.…”

Section: Clinical Relevancementioning

confidence: 99%

Heterogeneity in conduit artery function in humans: impact of arterial size

Thijssen¹,

Dawson²,

Black³

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

128

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To determine whether conduit artery size affects functional responses, we compared the magnitude, time course, and eliciting shear rate stimulus for flow-mediated dilation (FMD) in healthy men (n ϭ 20; 31 Ϯ 7 yr). Upper limb (brachial and radial) and lower limb (common and superficial femoral) FMD responses were simultaneously assessed, whereas popliteal responses were measured in the same subjects during a separate visit. Glyceryl trinitrate (GTN)-mediated responses were similarly examined. Edge detection and wall tracking of highresolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, were used to calculate conduit artery diameter, blood flow, and shear rate continuously across the cardiac cycle. Baseline artery size correlated inversely with the FMD response (r ϭ Ϫ0.57, P Ͻ 0.001). Within-artery comparisons revealed a significant inverse correlation between artery size and FMD% for the radial (r ϭ Ϫ0.66, P ϭ 0.001), brachial (r ϭ Ϫ0.55, P ϭ 0.01), and popliteal artery (r ϭ Ϫ0.48, P ϭ 0.03), but not for the superficial and common femoral artery. Normalization of FMD responses for differences in eliciting shear rate did not abolish the between-artery relationship for artery function and size (r ϭ Ϫ0.48, P Ͻ 0.001), suggesting that differences between artery function responses were not entirely due to size-related differences in shear rate. This was reinforced by a significant between-artery correlation for GTN responses and baseline artery size (r ϭ Ϫ0.74, P Ͻ 0.001). In summary, systematic differences exist in vascular function responses of conduit arteries that differ in size. This raises the possibility that differences in artery size within or between individuals may influence functional responses. flow-mediated dilation; nitroglycerine; arterial diameter; high-resolution ultrasound; Doppler MEASURES OF ARTERIAL FUNCTION have increasingly been adopted as surrogate markers of cardiovascular risk (31). For example, conduit artery vasodilation to a 5-min ischemic period, commonly referred to as flow-mediated dilation (FMD), reflects bioactivity of endothelium-derived nitric oxide (NO) (14, 17), which possesses myriad antiatherogenic effects (31). Endothelial dysfunction can be considered an early and integral manifestation of vascular disease that predicts cardiovascular events (8,15,16,18,21), whereas improvement in endothelial function impacts significantly on cardiovascular risk (10,11,16).For many years, it has been recognized that baseline artery diameter correlates strongly with the magnitude of the FMD response. It was recently proposed that this relationship might be explained as a consequence of smaller arteries being exposed, by virtue of their size, to a greater shear stress stimulus during reactive hyperemia. In relative terms, this results in enhanced dilator responses compared with arteries of larger dimension (25,27,28). Correcting the FMD response to the magnitude of the shear stress stimulus may eliminate the between-subject variability (23)....

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“…For each 45-second ultrasound Doppler segment, V mean was averaged across 15-second intervals of each recorded clip, with intima-to-intima diameter measurements evaluated during diastole, as described previously. 20,21 Because of the anticipated decline in maximal knee-extensor exercise capacity in older subjects, the a priori design was to assess responses at similar relative exercise intensities. However, posthoc analysis of responses using a single absolute work rate of 10 W was also performed to evaluate potential age-related differences at comparable levels of leg O 2 consumption.…”

Section: Data Analysis and Statisticsmentioning

confidence: 99%

Angiotensin II in the Elderly

et al. 2008

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Abstract-Exercise hyperemia is attenuated in the elderly, which may be attributed to local vasoregulatory pathways within the skeletal muscle vasculature. Therefore, we sought to determine whether healthy aging is associated with changes in angiotensin II (Ang II) receptor sensitivity through measurements of leg blood flow in resting and exercising skeletal muscle. In 12 (nϭ6 young, 24Ϯ1 years; nϭ6 older, 68Ϯ3 years) healthy volunteers, we determined changes in leg blood flow (ultrasound Doppler) before and during intra-arterial infusion of Ang II (0.8 ng/mL of leg blood flow per minute). Heart rate, arterial blood pressure, common femoral artery diameter, and mean blood velocity were measured at rest and during knee-extensor exercise at 20% and 40% of the maximal work rate (WR max ). At rest, Ang II infusion decreased leg blood flow to a greater extent in older (Ϫ61Ϯ8%) subjects compared with younger subjects (Ϫ31Ϯ5%). Compared with rest, Ang II-mediated vasoconstriction (leg blood flow) during exercise was diminished in both older and younger subjects at 20% (older: Ϫ7Ϯ5%; younger: Ϫ21Ϯ2%) and 40% WR max (older: Ϫ5Ϯ4%; younger: Ϫ9Ϯ3%). These data identify a clear age-related hypersensitivity to Ang II in the resting leg, which may contribute to the recognized decrement in leg blood flow in this cohort. However, the diminished vasoconstriction to Ang II during exercise suggests that the elevation in Ang II type 1 receptor sensitivity documented at rest does not contribute significantly to the blunted exercise hyperemia experienced with advancing age. Key Words: basic science Ⅲ elderly Ⅲ blood flow regulation Ⅲ exercise Ⅲ angiotensin receptors A ngiotensin II (Ang II) acts as a potent endogenous vasoconstrictor through binding to the Ang II type 1 (AT 1 ) receptor on arteriolar vascular smooth muscle. With advancing age, there is a notable decline in plasma renin activity 1 accompanied by small decrements in circulating Ang II 2 and an increase in AT 1 receptor density. 3,4 However, the functional consequence of this age-related adaptation of the renin-angiotensin system on the peripheral circulation is not well understood. Although the pressor response to systemic Ang II infusion is elevated with age, 5 no age-specific adaptation in AT 1 receptor sensitivity has been observed with local, intra-arterial Ang II infusion in the arm. 6 Together, these studies indicate a general decline in renin-angiotensin system function with age but with uncertainty as to the impact of these changes on end-organ function and skeletal muscle hemodynamics.AT 1 receptor sensitivity to Ang II in the elderly may be especially important in the context of underlying changes in autonomic function. It is well established that elevated vasoconstrictor tone as a consequence of high sympathetic nerve activity is present in healthy, older adults, 7-9 despite a reduction in the sensitivity of postjunctional adrenergic vascular receptors. 10 This capacity for sustained sympathetic vasoconstriction in the face of reduced adrenergic responsivenes...

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Differential effects of aging on limb blood flow in humans

Cited by 145 publications

References 42 publications

Ascorbate infusion increases skeletal muscle fatigue resistance in patients with chronic obstructive pulmonary disease

Ascorbate infusion increases skeletal muscle fatigue resistance in patients with chronic obstructive pulmonary disease

Heterogeneity in conduit artery function in humans: impact of arterial size

Angiotensin II in the Elderly

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