Document Detail


Influence of α-adrenergic vasoconstriction on the blunted skeletal muscle contraction-induced rapid vasodilation with aging.
MedLine Citation:
PMID:  22961267     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We tested the hypothesis that elevated sympathetic tone is responsible for lower peak vasodilation after single muscle contractions in older adults. Young (n = 13, 7 men and 6 women, age: 27 ± 1 yr) and older (n = 13, 7 men and 6 women, age: 69 ± 2 yr) adults performed single forearm contractions at 10%, 20%, and 40% of maximum during 1) control, 2) sympathetic activation via lower body negative pressure (LBNP; -20 mmHg), and 3) intra-arterial infusion of phentolamine (α-adrenergic antagonist). Brachial artery diameter and velocities were measured via Doppler ultrasound, and forearm vascular conductance (FVC; in ml·min(-1)·100 mmHg(-1)) was calculated from blood flow (in ml/min) and blood pressure (in mmHg). Peak vasodilator responses [change in (Δ) FVC from baseline] were attenuated in older adults at 20% and 40% of maximum (P < 0.05). LBNP reduced peak ΔFVC at 10% (98 ± 17 vs. 70 ± 12 ml·min(-1)·100 mmHg(-1)), 20% (144 ± 12 vs. 98 ± 3 ml·min(-1)·100 mmHg(-1)), and 40% (209 ± 20 vs. 161 ± 21 ml·min(-1)·100 mmHg(-1), P < 0.01 vs. control) in younger adults but not in older adults (71 ± 11 vs. 68 ± 11, 107 ± 13 vs. 106 ± 16, and 161 ± 22 vs. 144 ± 22 ml·min(-1)·100 mmHg(-1), respectively, P = 0.22-0.99). With phentolamine, peak ΔFVC was enhanced in older adults at each contraction intensity (100 ± 14, 147 ± 22, and 200 ± 26 ml·min(-1)·100 mmHg(-1), respectively, P < 0.01 vs. control) but not in younger adults (94 ± 13, 153 ± 13, and 224 ± 27 ml·min(-1)·100 mmHg(-1), respectively, P = 0.30-0.81 vs. control). Our data indicate that α-adrenergic vasoconstriction and/or blunted functional sympatholysis might contribute to the age-related decreases in skeletal muscle contraction-induced rapid vasodilation in humans.
Authors:
Darren P Casey; Michael J Joyner
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-09-06
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-16     Completed Date:  2013-06-17     Revised Date:  2013-10-17    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1201-12     Citation Subset:  IM    
Affiliation:
Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. casey.darren@mayo.edu
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MeSH Terms
Descriptor/Qualifier:
Adrenergic alpha-Antagonists / pharmacology*
Adult
Aged
Aging / physiology*
Blood Flow Velocity / drug effects,  physiology
Blood Pressure / drug effects,  physiology
Brachial Artery / drug effects,  physiology
Female
Forearm / blood supply,  physiology
Heart Rate / drug effects,  physiology
Hemodynamics / drug effects,  physiology
Humans
Infusions, Intra-Arterial / methods
Lower Body Negative Pressure / methods
Male
Muscle Contraction / drug effects,  physiology*
Muscle, Skeletal / blood supply,  drug effects,  physiology*
Phentolamine / pharmacology
Regional Blood Flow / drug effects,  physiology
Sympathetic Nervous System / drug effects,  physiology
Vasoconstriction / drug effects,  physiology*
Vasodilation / drug effects,  physiology*
Grant Support
ID/Acronym/Agency:
HL-105467/HL/NHLBI NIH HHS; HL-46493/HL/NHLBI NIH HHS; RR-024150/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 50-60-2/Phentolamine
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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