Journal article
Vasoconstrictor responsiveness during hyperbaric hyperoxia in contracting human muscle
Journal of applied physiology (1985), Vol.114(2), pp.217-224
01/15/2013
DOI: 10.1152/japplphysiol.01197.2012
PMCID: PMC3774558
PMID: 23154993
Abstract
Large increases in systemic oxygen content cause substantial reductions in exercising forearm blood flow (FBF) due to increased vascular resistance. We hypothesized that
1
) functional sympatholysis (blunting of sympathetic α-adrenergic vasoconstriction) would be attenuated during hyperoxic exercise and
2
) α-adrenergic blockade would limit vasoconstriction during hyperoxia and increase FBF to levels observed under normoxic conditions. Nine male subjects (age 28 ± 1 yr) performed forearm exercise (20% of maximum) under normoxic and hyperoxic conditions. Studies were performed in a hyperbaric chamber at 1 atmosphere absolute (ATA; sea level) while breathing 21% O
2
and at 2.82 ATA while breathing 100% O
2
(estimated change in arterial O
2
content ∼6 ml O
2
/100 ml). FBF (ml/min) was measured using Doppler ultrasound. Forearm vascular conductance (FVC) was calculated from FBF and blood pressure (arterial catheter). Vasoconstrictor responsiveness was determined using intra-arterial tyramine. FBF and FVC were substantially lower during hyperoxic exercise than normoxic exercise (∼20–25%;
P
< 0.01). At rest, vasoconstriction to tyramine (% decrease from pretyramine values) did not differ between normoxia and hyperoxia (
P
> 0.05). During exercise, vasoconstrictor responsiveness was slightly greater during hyperoxia than normoxia (−22 ± 3 vs. −17 ± 2%;
P
< 0.05). However, during α-adrenergic blockade, hyperoxic exercise FBF and FVC remained lower than during normoxia (
P
< 0.01). Therefore, our data suggest that although the vasoconstrictor responsiveness during hyperoxic exercise was slightly greater, it likely does not explain the majority of the large reductions in FBF and FVC (∼20–25%) during hyperbaric hyperoxic exercise.
Details
- Title: Subtitle
- Vasoconstrictor responsiveness during hyperbaric hyperoxia in contracting human muscle
- Creators
- Darren P Casey - Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; andMichael J Joyner - Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; andPaul L Claus - Division of Preventive, Occupational, and Aerospace Medicine, Mayo Clinic, Rochester, MinnesotaTimothy B Curry - Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; and
- Resource Type
- Journal article
- Publication Details
- Journal of applied physiology (1985), Vol.114(2), pp.217-224
- DOI
- 10.1152/japplphysiol.01197.2012
- PMID
- 23154993
- PMCID
- PMC3774558
- NLM abbreviation
- J Appl Physiol (1985)
- ISSN
- 8750-7587
- eISSN
- 1522-1601
- Publisher
- American Physiological Society; Bethesda, MD
- Grant note
- HL-46493; HL-105467 / National Institutes of Health
- Language
- English
- Date published
- 01/15/2013
- Academic Unit
- Physical Therapy and Rehabilitation Science; Fraternal Order of Eagles Diabetes Research Center
- Record Identifier
- 9984047625002771
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