Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters

Robert S. Mazzeo, Andrea Dubay, Jennifer Kirsch, Barry Braun, Gail E. Butterfield, Paul B. Rock, Eugene E. Wolfel, Stacy Zamudio, Lorna G. Moore

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

This investigation examined the influence of α-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 α-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 α-adrenergic activity over time at altitude were associated with select metabolic and physiologic adjustments. The presence of α-blockade significantly affected these responses during chronic altitude exposure. It was concluded that: (1) α- adrenergic blockade elicited a potentiated sympathoadrenal response to the stress of both exercise as well as high-altitude exposure, and (2) the sympathetics, via α-adrenergic stimulation, contribute to a number of key adaptations associated with acclimatization to high altitude.

Original languageEnglish
Pages (from-to)1471-1477
Number of pages7
JournalMetabolism: Clinical and Experimental
Volume52
Issue number11
DOIs
StatePublished - 1 Jan 2003

Fingerprint

Adrenergic Agents
Catecholamines
Exercise
Oceans and Seas
Norepinephrine
Epinephrine
Placebos
Prazosin
Acclimatization
Exercise Test
Oxygen Consumption
Urine

Cite this

Mazzeo, Robert S. ; Dubay, Andrea ; Kirsch, Jennifer ; Braun, Barry ; Butterfield, Gail E. ; Rock, Paul B. ; Wolfel, Eugene E. ; Zamudio, Stacy ; Moore, Lorna G. / Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters. In: Metabolism: Clinical and Experimental. 2003 ; Vol. 52, No. 11. pp. 1471-1477.
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Mazzeo, RS, Dubay, A, Kirsch, J, Braun, B, Butterfield, GE, Rock, PB, Wolfel, EE, Zamudio, S & Moore, LG 2003, 'Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters', Metabolism: Clinical and Experimental, vol. 52, no. 11, pp. 1471-1477. https://doi.org/10.1016/S0026-0495(03)00259-2

Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters. / Mazzeo, Robert S.; Dubay, Andrea; Kirsch, Jennifer; Braun, Barry; Butterfield, Gail E.; Rock, Paul B.; Wolfel, Eugene E.; Zamudio, Stacy; Moore, Lorna G.

In: Metabolism: Clinical and Experimental, Vol. 52, No. 11, 01.01.2003, p. 1471-1477.

Research output: Contribution to journalArticle

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T1 - Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters

AU - Mazzeo, Robert S.

AU - Dubay, Andrea

AU - Kirsch, Jennifer

AU - Braun, Barry

AU - Butterfield, Gail E.

AU - Rock, Paul B.

AU - Wolfel, Eugene E.

AU - Zamudio, Stacy

AU - Moore, Lorna G.

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N2 - This investigation examined the influence of α-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 α-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 α-adrenergic activity over time at altitude were associated with select metabolic and physiologic adjustments. The presence of α-blockade significantly affected these responses during chronic altitude exposure. It was concluded that: (1) α- adrenergic blockade elicited a potentiated sympathoadrenal response to the stress of both exercise as well as high-altitude exposure, and (2) the sympathetics, via α-adrenergic stimulation, contribute to a number of key adaptations associated with acclimatization to high altitude.

AB - This investigation examined the influence of α-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 α-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 α-adrenergic activity over time at altitude were associated with select metabolic and physiologic adjustments. The presence of α-blockade significantly affected these responses during chronic altitude exposure. It was concluded that: (1) α- adrenergic blockade elicited a potentiated sympathoadrenal response to the stress of both exercise as well as high-altitude exposure, and (2) the sympathetics, via α-adrenergic stimulation, contribute to a number of key adaptations associated with acclimatization to high altitude.

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