Journal article
α-adrenergic vasoconstriction contributes to the age-related increase in conduit artery retrograde and oscillatory shear
Hypertension (Dallas, Tex. 1979), Vol.60(4), pp.1016-1022
10/2012
DOI: 10.1161/HYPERTENSIONAHA.112.200618
PMCID: PMC3483145
PMID: 22949528
Abstract
Aging is associated with increased retrograde and oscillatory shear in peripheral conduit arteries of humans. Although the mechanisms responsible for these age-related changes are not completely understood, augmented downstream α-adrenergic tone likely plays a significant role in this phenomenon. Therefore, in protocol 1, brachial artery diameter and blood velocity were measured via Doppler ultrasound during (1) rest (control), (2) endogenous norepinephrine release via intra-arterial infusions of tyramine, and (3) α-adrenergic blockade via infusions of phentolamine in young healthy humans (n=12). Tyramine increased brachial artery retrograde (-4.0±1.4 to -9.5±1.4 s(-1)) and oscillatory shear (0.05±0.02 to 0.18±0.05 arbitrary units), whereas phentolamine abolished retrograde and oscillatory shear (P<0.05). Additionally, in protocol 2, we examined brachial artery shear patterns in young (n=12; 29±2 years) and older (n=13; 69±2 years) healthy adults during (1) rest (control), (2) sympathetic activation via lower body negative pressure, and (3) infusion of phentolamine. At rest, older adults exhibited greater brachial artery retrograde and oscillatory shear (-9.9±2.7 s(-1) and 0.11±0.03 arbitrary units, respectively) compared with younger adults (-3.1±1.0 s(-1) and 0.05±0.02 arbitrary units, respectively; P<0.05 for both). Lower body negative pressure increased retrograde and oscillatory shear in young (P<0.05), but not older adults (P=0.85-0.97), such that differences between young and older were eliminated (P>0.05). During infusion of phentolamine, retrograde and oscillatory shear were abolished in young adults (P<0.05) and markedly reduced, yet still persistent, in older adults (P<0.01). Our data indicate that α-adrenergic vasoconstriction is a major contributor to age-related discrepancies in conduit artery shear-rate patterns at rest.
Details
- Title: Subtitle
- α-adrenergic vasoconstriction contributes to the age-related increase in conduit artery retrograde and oscillatory shear
- Creators
- Darren P Casey - Department of Anesthesiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA. casey.darren@mayo.eduJaume PadillaMichael J Joyner
- Resource Type
- Journal article
- Publication Details
- Hypertension (Dallas, Tex. 1979), Vol.60(4), pp.1016-1022
- Publisher
- United States
- DOI
- 10.1161/HYPERTENSIONAHA.112.200618
- PMID
- 22949528
- PMCID
- PMC3483145
- ISSN
- 0194-911X
- eISSN
- 1524-4563
- Grant note
- K99 HL105467 / NHLBI NIH HHS UL1 RR024150 / NCRR NIH HHS HL-46493 / NHLBI NIH HHS R00 HL105467 / NHLBI NIH HHS R01 HL046493 / NHLBI NIH HHS RR-024150 / NCRR NIH HHS HL-105467 / NHLBI NIH HHS
- Language
- English
- Date published
- 10/2012
- Academic Unit
- Physical Therapy and Rehabilitation Science; Fraternal Order of Eagles Diabetes Research Center
- Record Identifier
- 9984046800802771
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