| Influence of alpha-adrenergic blockade on the catecholamine response to exercise at 4,300 meters. | |
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MedLine Citation:
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PMID: 14624409 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This investigation examined the influence of alpha-adrenergic blockade on plasma and urinary catecholamine responses to both exercise and high-altitude exposure. Sixteen nonsmoking, eumenorrheic women (age 23.2 +/- 1.4 years, 68.7 +/- 1.0 kg) were studied at sea level and during 12 days of high-altitude exposure (4,300 m). Subjects received either alpha-blockade (prazosin 3 mg/d) or a placebo in a double-blinded, randomized fashion. Resting plasma and 24-hour urine samples were collected periodically throughout the duration of the study. Further, subjects participated in submaximal exercise tests (50 minutes at 50% sea level maximum oxygen consumption [Vo2max]) at Sea level and on days 1 and 12 at altitude. Urinary norepinephrine (NE) excretion rates increased significantly over time at altitude, with blocked subjects having greater values compared to controls. Plasma NE levels increased significantly with chronic altitude exposure compared to sea level and acute hypoxia both at rest and during exercise. NE levels at rest were greater for blocked compared to control subjects during all conditions. Urinary and plasma epinephrine (EPI) levels increased dramatically, with acute altitude exposure returning to sea level values by day 12 of altitude exposure. EPI levels were greater for blocked compared to placebo both at rest and during exercise for all conditions studied. Changes in alpha-adrenergic activity over time at altitude were associated with select metabolic and physiologic adjustments. The presence of alpha-blockade significantly affected these responses during chronic altitude exposure. It was concluded that: (1) alpha-adrenergic blockade elicited a potentiated sympathoadrenal response to the stress of both exercise as well as high-altitude exposure, and (2) the sympathetics, via alpha-adrenergic stimulation, contribute to a number of key adaptations associated with acclimatization to high altitude. |
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Authors:
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Robert S Mazzeo; Andrea Dubay; Jennifer Kirsch; Barry Braun; Gail E Butterfield; Paul B Rock; Eugene E Wolfel; Stacy Zamudio; Lorna G Moore |
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Publication Detail:
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Type: Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Metabolism: clinical and experimental Volume: 52 ISSN: 0026-0495 ISO Abbreviation: Metab. Clin. Exp. Publication Date: 2003 Nov |
Date Detail:
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Created Date: 2003-11-19 Completed Date: 2003-12-12 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0375267 Medline TA: Metabolism Country: United States |
Other Details:
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Languages: eng Pagination: 1471-7 Citation Subset: IM |
Affiliation:
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Department of Kinesiology and Applied Physiology, University of Colorado, Boulder 80309, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acclimatization
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drug effects,
physiology Adrenergic alpha-Agonists / pharmacology Adrenergic alpha-Antagonists / pharmacology* Adult Altitude* Basal Metabolism / drug effects, physiology Catecholamines / blood*, urine Double-Blind Method Estradiol / blood Exercise / physiology* Female Humans Menstrual Cycle / physiology Oxygen Consumption / drug effects, physiology Phenylephrine / pharmacology Plasma Volume / drug effects, physiology Prazosin / pharmacology Progesterone / blood Sympathetic Nervous System / drug effects, physiology |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Agonists; 0/Adrenergic alpha-Antagonists; 0/Catecholamines; 19216-56-9/Prazosin; 50-28-2/Estradiol; 57-83-0/Progesterone; 59-42-7/Phenylephrine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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