Women at altitude: Forearm hemodynamics during acclimatization to 4,300 m with α 1 -adrenergic blockade

Stacy Zamudio, Matthew Douglas, Robert S. Mazzeo, Eugene E. Wolfel, David A. Young, Paul Rock, Barry Braun, Stephen R. Muza, Gail E. Butterfield, Lorna G. Moore

Research output: Contribution to journalArticle

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Abstract

We hypothesized that blockade of α 1 -adrenergic receptors would prevent the rise in peripheral vascular resistance that normally occurs during acclimatization. Sixteen eumenorrheic women were studied at sea level (SL) and at 4,300 m (days 3 and 10). Volunteers were randomly assigned to take the selective α 1 -blocker prazosin or placebo. Venous compliance, forearm vascular resistance, and blood flow were measured using plethysmography. Venous compliance fell by day 3 in all subjects (1.39 ± 0.30 vs. 1.62 ± 0.43 ml·Δ30 mmHg -1 ·100 ml tissue -1 ·min -1 at SL, means ± SD). Altitude interacted with prazosin treatment (P < 0.0001) such that compliance returned to SL values by day 10 in the prazosin-treated group (1.68 ÷± 0.19) but not in the placebo-treated group (1.20 ± 0.10, P < 0.05). By day 3 at 4,300 m, all women had significant falls in resistance (35.2 ± 13.2 vs. 54.5 ± 16.1 mmHg·ml -1 ·min -1 at SL) and rises in blood flow (2.5 ± 1.0 vs. 1.6 ± 0.5 ml·100 ml tissue -1 ·min -1 at SL). By day 10, resistance and flow returned toward SL, but this return was less in the prazosin-treated group (resistance: 39.8 ± 4.6 mmHg·ml -1 ·min -1 with prazosin vs. 58.5 ± 9.8 mmHg·ml -1 ·min -1 with placebo; flow: 1.9 ± 0.7 ml·100 ml tissue -1 ·min -1 with prazosin vs. 2.3 ± 0.3 ml·100 ml tissue -1 ·min -1 with placebo, P < 0.05). Lower resistance related to higher circulating epinephrine in both groups (r = -0.50, P < 0.0001). Higher circulating norepinephrine related to lower venous compliance in the placebo-treated group (r = -0.42, P < 0.05). We conclude that α 1 -adrenergic stimulation modulates peripheral vascular changes during acclimatization.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume281
Issue number6 50-6
StatePublished - 1 Dec 2001

Fingerprint

Prazosin
Acclimatization
Forearm
Oceans and Seas
Adrenergic Agents
Hemodynamics
Placebos
Compliance
Vascular Resistance
Plethysmography
Adrenergic Receptors
Epinephrine
Blood Vessels
Volunteers
Norepinephrine

Keywords

  • Epinephrine
  • High altitude
  • Hypoxia
  • Neropinephrine
  • Peripheral blood flow
  • Prazosin
  • Vascular resistance
  • Venous compliance

Cite this

Zamudio, Stacy ; Douglas, Matthew ; Mazzeo, Robert S. ; Wolfel, Eugene E. ; Young, David A. ; Rock, Paul ; Braun, Barry ; Muza, Stephen R. ; Butterfield, Gail E. ; Moore, Lorna G. / Women at altitude : Forearm hemodynamics during acclimatization to 4,300 m with α 1 -adrenergic blockade. In: American Journal of Physiology - Heart and Circulatory Physiology. 2001 ; Vol. 281, No. 6 50-6.
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abstract = "We hypothesized that blockade of α 1 -adrenergic receptors would prevent the rise in peripheral vascular resistance that normally occurs during acclimatization. Sixteen eumenorrheic women were studied at sea level (SL) and at 4,300 m (days 3 and 10). Volunteers were randomly assigned to take the selective α 1 -blocker prazosin or placebo. Venous compliance, forearm vascular resistance, and blood flow were measured using plethysmography. Venous compliance fell by day 3 in all subjects (1.39 ± 0.30 vs. 1.62 ± 0.43 ml·Δ30 mmHg -1 ·100 ml tissue -1 ·min -1 at SL, means ± SD). Altitude interacted with prazosin treatment (P < 0.0001) such that compliance returned to SL values by day 10 in the prazosin-treated group (1.68 ÷± 0.19) but not in the placebo-treated group (1.20 ± 0.10, P < 0.05). By day 3 at 4,300 m, all women had significant falls in resistance (35.2 ± 13.2 vs. 54.5 ± 16.1 mmHg·ml -1 ·min -1 at SL) and rises in blood flow (2.5 ± 1.0 vs. 1.6 ± 0.5 ml·100 ml tissue -1 ·min -1 at SL). By day 10, resistance and flow returned toward SL, but this return was less in the prazosin-treated group (resistance: 39.8 ± 4.6 mmHg·ml -1 ·min -1 with prazosin vs. 58.5 ± 9.8 mmHg·ml -1 ·min -1 with placebo; flow: 1.9 ± 0.7 ml·100 ml tissue -1 ·min -1 with prazosin vs. 2.3 ± 0.3 ml·100 ml tissue -1 ·min -1 with placebo, P < 0.05). Lower resistance related to higher circulating epinephrine in both groups (r = -0.50, P < 0.0001). Higher circulating norepinephrine related to lower venous compliance in the placebo-treated group (r = -0.42, P < 0.05). We conclude that α 1 -adrenergic stimulation modulates peripheral vascular changes during acclimatization.",
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Zamudio, S, Douglas, M, Mazzeo, RS, Wolfel, EE, Young, DA, Rock, P, Braun, B, Muza, SR, Butterfield, GE & Moore, LG 2001, 'Women at altitude: Forearm hemodynamics during acclimatization to 4,300 m with α 1 -adrenergic blockade', American Journal of Physiology - Heart and Circulatory Physiology, vol. 281, no. 6 50-6.

Women at altitude : Forearm hemodynamics during acclimatization to 4,300 m with α 1 -adrenergic blockade. / Zamudio, Stacy; Douglas, Matthew; Mazzeo, Robert S.; Wolfel, Eugene E.; Young, David A.; Rock, Paul; Braun, Barry; Muza, Stephen R.; Butterfield, Gail E.; Moore, Lorna G.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 281, No. 6 50-6, 01.12.2001.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Women at altitude

T2 - Forearm hemodynamics during acclimatization to 4,300 m with α 1 -adrenergic blockade

AU - Zamudio, Stacy

AU - Douglas, Matthew

AU - Mazzeo, Robert S.

AU - Wolfel, Eugene E.

AU - Young, David A.

AU - Rock, Paul

AU - Braun, Barry

AU - Muza, Stephen R.

AU - Butterfield, Gail E.

AU - Moore, Lorna G.

PY - 2001/12/1

Y1 - 2001/12/1

N2 - We hypothesized that blockade of α 1 -adrenergic receptors would prevent the rise in peripheral vascular resistance that normally occurs during acclimatization. Sixteen eumenorrheic women were studied at sea level (SL) and at 4,300 m (days 3 and 10). Volunteers were randomly assigned to take the selective α 1 -blocker prazosin or placebo. Venous compliance, forearm vascular resistance, and blood flow were measured using plethysmography. Venous compliance fell by day 3 in all subjects (1.39 ± 0.30 vs. 1.62 ± 0.43 ml·Δ30 mmHg -1 ·100 ml tissue -1 ·min -1 at SL, means ± SD). Altitude interacted with prazosin treatment (P < 0.0001) such that compliance returned to SL values by day 10 in the prazosin-treated group (1.68 ÷± 0.19) but not in the placebo-treated group (1.20 ± 0.10, P < 0.05). By day 3 at 4,300 m, all women had significant falls in resistance (35.2 ± 13.2 vs. 54.5 ± 16.1 mmHg·ml -1 ·min -1 at SL) and rises in blood flow (2.5 ± 1.0 vs. 1.6 ± 0.5 ml·100 ml tissue -1 ·min -1 at SL). By day 10, resistance and flow returned toward SL, but this return was less in the prazosin-treated group (resistance: 39.8 ± 4.6 mmHg·ml -1 ·min -1 with prazosin vs. 58.5 ± 9.8 mmHg·ml -1 ·min -1 with placebo; flow: 1.9 ± 0.7 ml·100 ml tissue -1 ·min -1 with prazosin vs. 2.3 ± 0.3 ml·100 ml tissue -1 ·min -1 with placebo, P < 0.05). Lower resistance related to higher circulating epinephrine in both groups (r = -0.50, P < 0.0001). Higher circulating norepinephrine related to lower venous compliance in the placebo-treated group (r = -0.42, P < 0.05). We conclude that α 1 -adrenergic stimulation modulates peripheral vascular changes during acclimatization.

AB - We hypothesized that blockade of α 1 -adrenergic receptors would prevent the rise in peripheral vascular resistance that normally occurs during acclimatization. Sixteen eumenorrheic women were studied at sea level (SL) and at 4,300 m (days 3 and 10). Volunteers were randomly assigned to take the selective α 1 -blocker prazosin or placebo. Venous compliance, forearm vascular resistance, and blood flow were measured using plethysmography. Venous compliance fell by day 3 in all subjects (1.39 ± 0.30 vs. 1.62 ± 0.43 ml·Δ30 mmHg -1 ·100 ml tissue -1 ·min -1 at SL, means ± SD). Altitude interacted with prazosin treatment (P < 0.0001) such that compliance returned to SL values by day 10 in the prazosin-treated group (1.68 ÷± 0.19) but not in the placebo-treated group (1.20 ± 0.10, P < 0.05). By day 3 at 4,300 m, all women had significant falls in resistance (35.2 ± 13.2 vs. 54.5 ± 16.1 mmHg·ml -1 ·min -1 at SL) and rises in blood flow (2.5 ± 1.0 vs. 1.6 ± 0.5 ml·100 ml tissue -1 ·min -1 at SL). By day 10, resistance and flow returned toward SL, but this return was less in the prazosin-treated group (resistance: 39.8 ± 4.6 mmHg·ml -1 ·min -1 with prazosin vs. 58.5 ± 9.8 mmHg·ml -1 ·min -1 with placebo; flow: 1.9 ± 0.7 ml·100 ml tissue -1 ·min -1 with prazosin vs. 2.3 ± 0.3 ml·100 ml tissue -1 ·min -1 with placebo, P < 0.05). Lower resistance related to higher circulating epinephrine in both groups (r = -0.50, P < 0.0001). Higher circulating norepinephrine related to lower venous compliance in the placebo-treated group (r = -0.42, P < 0.05). We conclude that α 1 -adrenergic stimulation modulates peripheral vascular changes during acclimatization.

KW - Epinephrine

KW - High altitude

KW - Hypoxia

KW - Neropinephrine

KW - Peripheral blood flow

KW - Prazosin

KW - Vascular resistance

KW - Venous compliance

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M3 - Article

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JO - American Journal of Physiology - Heart and Circulatory Physiology

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SN - 0363-6135

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