Hypoxia-induced vasodilation and effects of regional phentolamine in awake patients with sleep apnea

Raman Moradkhan, Brett Spitnale, Patrick McQuillan, Cynthia Hogeman, Kristen S. Gray, Urs A. Leuenberger

Research output: Contribution to journalArticle

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Abstract

Obstructive sleep apnea (OSA.) is associated with increased sympathetic nerve activity, endothelial dysfunction, and premature cardiovascular disease. To determine whether hypoxia is associated with impaired skeletal muscle vasodilation, we compared femoral artery blood flow (ultrasound) and muscle sympathetic nerve activity (peroneal microneurography) during exposure to acute systemic hypoxia (fraction of inspired oxygen. 0.1) in awake patients with OSA (n = 10) and controls (n = 8). To assess the role of elevated sympathetic nerve activity, in a separate group of patients with OSA. (n = 10) and controls (n = 10) we measured brachial artery blood flow during hypoxia before and after regional α-adrenergic block with phentolamine. Despite elevated sympathetic activity, in OSA. the vascular responses to hypoxia in the leg did not differ significantly from those in controls [P = not significant (NS)]. Following regional phentolamine, in both groups the hypoxia-induced increase in brachial blood flow was markedly enhanced (OSA pre vs. post, 84 ± 13 vs. 201 ±34 ml/min, P < 0.002; controls pre vs. post 62 ± 8 vs. 140 ± 26 ml/min, P < 0.01). At end hypoxia after phentolamine, the increase of brachial blood flow above baseline was similar (OSA vs. controls +61 ± 16 vs. +48 ± 6%; P = NS). We conclude that despite high sympathetic vasoconstrictor tone and prominent sympathetic responses to acute hypoxia, hypoxia-induced limb vasodilation is preserved in OSA.

Original languageEnglish (US)
Pages (from-to)1234-1240
Number of pages7
JournalJournal of applied physiology
Volume108
Issue number5
DOIs
StatePublished - May 1 2010

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Phentolamine
Sleep Apnea Syndromes
Vasodilation
Obstructive Sleep Apnea
Arm
Peroneal Nerve
Brachial Artery
Hypoxia
Vasoconstrictor Agents
Femoral Artery
Adrenergic Agents
Blood Vessels
Leg
Skeletal Muscle
Cardiovascular Diseases
Extremities
Oxygen
Muscles

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

Moradkhan, Raman ; Spitnale, Brett ; McQuillan, Patrick ; Hogeman, Cynthia ; Gray, Kristen S. ; Leuenberger, Urs A. / Hypoxia-induced vasodilation and effects of regional phentolamine in awake patients with sleep apnea. In: Journal of applied physiology. 2010 ; Vol. 108, No. 5. pp. 1234-1240.
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Hypoxia-induced vasodilation and effects of regional phentolamine in awake patients with sleep apnea. / Moradkhan, Raman; Spitnale, Brett; McQuillan, Patrick; Hogeman, Cynthia; Gray, Kristen S.; Leuenberger, Urs A.

In: Journal of applied physiology, Vol. 108, No. 5, 01.05.2010, p. 1234-1240.

Research output: Contribution to journalArticle

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