Exposure to nitrogen dioxide is not associated with vascular dysfunction in man.
BACKGROUND
Exposure to air pollution is associated with increased cardiorespiratory morbidity and mortality. It is unclear whether these effects are mediated through combustion-derived particulate matter or gaseous components, such as nitrogen dioxide.


OBJECTIVE
To investigate the effect of nitrogen dioxide exposure on vascular vasomotor and six fibrinolytic functions.


METHODS
Ten healthy male volunteers were exposed to nitrogen dioxide at 4 ppm or filtered air for 1 h during intermittent exercise in a randomized double-blind crossover study. Bilateral forearm blood flow and fibrinolytic markers were measured before and during unilateral intrabrachial infusion of bradykinin (100-1000 pmol/min), acetylcholine (5-20 microg/min), sodium nitroprusside (2-8 microg/min), and verapamil (10-100 microg/min) 4 h after the exposure. Lung function was determined before and after the exposure, and exhaled nitric oxide at baseline and 1 and 4 h after the exposure.


RESULTS
There were no differences in resting forearm blood flow after either exposure. There was a dose-dependent increase in forearm blood flow with all vasodilators but this was similar after either exposure for all vasodilators (p > .05 for all). Bradykinin caused a dose-dependent increase in plasma tissue-plasminogen activator, but again there was no difference between the exposures. There were no changes in lung function or exhaled nitric oxide following either exposure.


CONCLUSIONS
Inhalation of nitrogen dioxide does not impair vascular vasomotor or fibrinolytic function. Nitrogen dioxide does not appear to be a major arbiter of the adverse cardiovascular effects of air pollution.
Langrish
Jeremy P
JP
Centre for Cardiovascular Sciences, University of Edinburgh, United Kingdom.
Lundbäck
Magnus
M
Barath
Stefan
S
Söderberg
Stefan
S
Mills
Nicholas L
NL
Newby
David E
DE
Sandström
Thomas
T
Blomberg
Anders
A
D000328:Adult; D000395:Air Pollutants, Occupational / Q000378:metabolism / Q000633:toxicity*; D001772:Blood Cell Count; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology; D015444:Exercise / Q000502:physiology; D005342:Fibrinolysis / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D019570:Inhalation Exposure; D008168:Lung / Q000187:drug effects; D008297:Male; D009585:Nitrogen Dioxide / Q000378:metabolism / Q000633:toxicity*; D010083:Oxidants, Photochemical / Q000378:metabolism / Q000633:toxicity*; D010960:Plasminogen Activators / Q000378:metabolism; D012129:Respiratory Function Tests; D013147:Spirometry; D013927:Thrombosis / Q000097:blood; D014652:Vascular Diseases / Q000139:chemically induced* / Q000453:epidemiology / Q000473:pathology; D055815:Young Adult
D000395:Air Pollutants, Occupational; D010083:Oxidants, Photochemical; D010960:Plasminogen Activators; D009585:Nitrogen Dioxide