Contraction mediated blunting of postjunctional α-adrenergic vasoconstriction (functional sympatholysis) is attenuated in older males; however, direct confirmation of this effect remains unknown in postmenopausal women (PMW). The present study examined whether PMW exhibit augmented postjunctional α-adrenergic receptor vasoconstriction at rest and during forearm exercise compared to young women (YW). Eight YW (24 ± 1 yrs) and eight PMW (65 ± 1 yrs) completed a series of randomized experimental trials; 1) at rest 2) under high flow (adenosine infusion) conditions and 3) during 6-minutes of forearm exercise at relative (20% of maximum (MVC) and absolute (7 kg) intensities. Phenylephrine (α1 -agonist) or dexmedetomidine (α2 -agonist) was administered during the last 3-minutes of each trial to elicit α-adrenergic vasoconstriction. Forearm vascular conductance (FVC) was calculated from blood flow and blood pressure. Vasoconstrictor responsiveness was identified as the change in FVC (%) during α-adrenergic agonist infusions from baseline (resting trial) or from steady-state conditions (high flow and exercise trials). During resting and high-flow trials, the %FVC during α1 - and α2 -agonist stimulation was similar between YW and PMW. During exercise, α1 -mediated vasoconstriction was blunted in YW vs. PMW at relative (-6 ± 2% vs. -15 ± 3%) and absolute (-4 ± 2% vs. -14 ± 5%) workloads, such that blood flow and FVC were lower in PMW (P<0.05 for all). Conversely, α2 -mediated vasoconstriction was similar between YW and PMW at relative (-22 ± 3% vs. -22 ± 4%; P>0.05) and absolute (-19 ± 3% vs. -18 ± 4%; P>0.05) workloads. Collectively, these findings demonstrate that despite similar α-adrenergic vasoconstrictor responsiveness at rest, PMW have a decreased ability to attenuate α1 -adrenergic vasoconstriction in contracting skeletal muscle. This article is protected by copyright. All rights reserved.
This research output has an Altmetric Attention Score of 4. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 14 July 2018.
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#11,825,413
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Altmetric has tracked 34,376,207 research outputs across all sources so far. This one has received more attention than most of these and is in the 65th percentile.
So far Altmetric has tracked 12,248 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 12.4. This one has gotten more attention than average, scoring higher than 60% of its peers.
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