Nitric oxide contributes to the augmented vasodilatation during hypoxic exercise

Darren P Casey; Brandon D Madery; Timothy B Curry; John H Eisenach; Brad W Wilkins; Michael J Joyner

doi:10.1113/jphysiol.2009.180489

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Nitric oxide contributes to the augmented vasodilatation during hypoxic exercise

Journal article

Open access

Peer reviewed

Nitric oxide contributes to the augmented vasodilatation during hypoxic exercise

Darren P Casey, Brandon D Madery, Timothy B Curry, John H Eisenach, Brad W Wilkins and Michael J Joyner

The Journal of physiology, Vol.588(Pt 2), pp.373-385

01/15/2010

DOI: 10.1113/jphysiol.2009.180489

PMCID: PMC2821731

PMID: 19948661

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Abstract

We tested the hypotheses that (1) nitric oxide (NO) contributes to augmented skeletal muscle vasodilatation during hypoxic exercise and (2) the combined inhibition of NO production and adenosine receptor activation would attenuate the augmented vasodilatation during hypoxic exercise more than NO inhibition alone. In separate protocols subjects performed forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O(2) saturation). In protocol 1 (n = 12), subjects received intra-arterial administration of saline (control) and the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA). In protocol 2 (n = 10), subjects received intra-arterial saline (control) and combined L-NMMA-aminophylline (adenosine receptor antagonist) administration. Forearm vascular conductance (FVC; ml min(-1) (100 mmHg)(-1)) was calculated from forearm blood flow (ml min(-1)) and blood pressure (mmHg). In protocol 1, the change in FVC (Delta from normoxic baseline) due to hypoxia under resting conditions and during hypoxic exercise was substantially lower with L-NMMA administration compared to saline (control; P < 0.01). In protocol 2, administration of combined L-NMMA-aminophylline reduced the DeltaFVC due to hypoxic exercise compared to saline (control; P < 0.01). However, the relative reduction in DeltaFVC compared to the respective control (saline) conditions was similar between L-NMMA only (protocol 1) and combined L-NMMA-aminophylline (protocol 2) at 10% (-17.5 +/- 3.7 vs. -21.4 +/- 5.2%; P = 0.28) and 20% (-13.4 +/- 3.5 vs. -18.8 +/- 4.5%; P = 0.18) hypoxic exercise. These findings suggest that NO contributes to the augmented vasodilatation observed during hypoxic exercise independent of adenosine.

Aminophylline - pharmacology

Humans

Enzyme Inhibitors - pharmacology

Male

Nitric Oxide - physiology

omega-N-Methylarginine - pharmacology

Cardiotonic Agents - pharmacology

Muscle, Skeletal - physiology

Regional Blood Flow - drug effects

Analysis of Variance

Muscle, Skeletal - drug effects

Forearm - blood supply

Adult

Female

Hypoxia - physiopathology

Blood Pressure - drug effects

Blood Pressure - physiology

Exercise - physiology

Vasodilation - drug effects

Vasodilation - physiology

Regional Blood Flow - physiology

Muscle, Skeletal - blood supply

Details

Title: Subtitle: Nitric oxide contributes to the augmented vasodilatation during hypoxic exercise
Creators: Darren P Casey - Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA. casey.darren@mayo.edu
Brandon D Madery
Timothy B Curry
John H Eisenach
Brad W Wilkins
Michael J Joyner
Resource Type: Journal article
Publication Details: The Journal of physiology, Vol.588(Pt 2), pp.373-385
DOI: 10.1113/jphysiol.2009.180489
PMID: 19948661
PMCID: PMC2821731
NLM abbreviation: J Physiol
ISSN: 0022-3751
eISSN: 1469-7793
Publisher: England
Grant note: UL1 RR024150 / NCRR NIH HHS HL-46493 / NHLBI NIH HHS R01 HL046493 / NHLBI NIH HHS AR-55819 / NIAMS NIH HHS RR-024150 / NCRR NIH HHS F32 AR055819 / NIAMS NIH HHS
Language: English
Date published: 01/15/2010
Academic Unit: Physical Therapy and Rehabilitation Science; Fraternal Order of Eagles Diabetes Research Center
Record Identifier: 9984047786402771

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