| alpha-adrenergic vasoconstriction in active skeletal muscles during dynamic exercise. | |
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MedLine Citation:
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PMID: 10409179 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Sympathetic vasoconstriction in working muscles during dynamic exercise has been demonstrated by intra-arterial administration of alpha(1)-adrenergic antagonists. The purpose of this study was to examine the existence of alpha(1)- and alpha(2)-adrenergic receptor-mediated vasoconstriction in active skeletal muscles during exercise. Six mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs, and a catheter was inserted in one femoral artery. All dogs ran on a motorized treadmill at three exercise intensities (3 miles/h, 6 miles/h, and 6 miles/h at 10% grade) on separate days. After 5 min of exercise, a selective alpha(1)- (prazosin) or a selective alpha(2)-adrenergic antagonist (rauwolscine) was infused as a bolus into the femoral arterial catheter (only one drug per day). The doses of the antagonists were adjusted to maintain the same effective concentration at each exercise intensity. At the mild, moderate, and heavy workloads prazosin infusion produced immediate increases in iliac conductance of 65 +/- 9, 35 +/- 6, and 18 +/- 4% (means +/- SE), respectively, and increases in blood flow of 290 +/- 24, 216 +/- 23, and 172 +/- 18 ml/min, respectively. Rauwolscine infusion produced increases in conductance of 52 +/- 5%, 36 +/- 5%, and 26 +/- 3%, respectively, and blood flow increases of 250 +/- 34, 244 +/- 39, and 259 +/- 35 ml/min at the three workloads. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected by any of the antagonist infusions. These results demonstrate that there is ongoing alpha(1)- and alpha(2)-adrenergic receptor-mediated vasoconstriction in exercising skeletal muscles even at heavy workloads and that the magnitude of vasoconstriction decreases as exercise intensity increases. |
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Authors:
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J B Buckwalter; P S Clifford |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The American journal of physiology Volume: 277 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1999 Jul |
Date Detail:
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Created Date: 1999-08-30 Completed Date: 1999-08-30 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: H33-9 Citation Subset: IM; S |
Affiliation:
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Departments of Anesthesiology and Physiology, Medical College of Wisconsin and Veterans Affairs Medical Center, Milwaukee, Wisconsin 53295, USA. jbuckwal@mcw.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-Antagonists
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pharmacology Animals Dogs Muscle, Skeletal / drug effects, physiology* Physical Conditioning, Animal / physiology* Prazosin / pharmacology Receptors, Adrenergic, alpha / drug effects, physiology* Vasoconstriction / drug effects, physiology* Yohimbine / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Antagonists; 0/Receptors, Adrenergic, alpha; 146-48-5/Yohimbine; 19216-56-9/Prazosin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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