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Ascorbic acid attenuates sympathetic activation and endothelial dysfunction induced by short‐term intermittent hypoxia in humans
Author(s) -
Leuenberger Urs A.,
Linton-Frazier Latoya,
Spilk Samson,
Hogeman Cynthia
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.898.6
Subject(s) - ascorbic acid , intermittent hypoxia , medicine , endocrinology , sympathetic nervous system , oxidative stress , endothelial dysfunction , hypoxia (environmental) , brachial artery , saline , bradycardia , chemistry , blood pressure , obstructive sleep apnea , anesthesia , heart rate , oxygen , organic chemistry , food science
In healthy humans, short‐term intermittent hypoxia (IH) raises sympathetic nerve activity mirroring the sympathetic activation seen in patients with obstructive sleep apnea. To explore the role of oxidative stress, we measured blood pressure (BP), sympathetic activity (microneurography) and flow‐mediated brachial artery dilation before and following IH (30 episodes, O 2 saturation nadir ~82%) with and without the antioxidant ascorbic acid (50 mg/kg iv) in healthy subjects (age 26±1 yrs; n=13). During saline infusion, IH produced a sustained increase in sympathetic activity (pre vs. post 20.0±1.8 vs. 25.2±1.8 bursts/min; P <0.05) and a small rise of mean BP (pre vs. post 86±2 vs. 89±3 mmHg; P <0.05). In contrast, on a separate day during infusion of ascorbic acid, IH did not raise sympathetic activity (pre vs. post 20.2±2.1 vs. 20.5±2.6 bursts/min; P =NS) or BP (pre vs. post 88±2 vs. 89±2 mmHg; P =NS). Moreover, whereas during saline infusion IH reduced flow‐mediated dilation (pre vs. post 6.8±1.3 vs. 3.2±1.6%; P <0.05), with ascorbic acid this effect was not seen (pre vs. post 6.0±1.2 vs. 6.1±1.4%; P =NS, n=8). These data suggest indirectly that oxidative stress may play a role in the sympathetic activation and vascular dysfunction induced by IH. Supported by P01 HL077670 and UL1 RR033184 .