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Airway responses to methacholine and exercise at high altitude in healthy lowlanders

Pellegrino, Riccardo
Pompilio, Pasquale
Quaranta, Marco
Aliverti, Andrea
Miserocchi, Giuseppe
Fasano, Valter
Cogo, Annalisa
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Published in Journal of Applied Physiology. 2010, vol. 108, no. 2, p. 256-65
Abstract Peribronchial edema has been proposed as a mechanism enhancing airway responses to constrictor stimuli. Acute exposure to altitude in nonacclimatized lowlanders leads to subclinical interstitial pulmonary edema that lasts for several days after ascent, as suggested by changes in lung mechanics. We, therefore, investigated whether changes in lung mechanics consistent with fluid accumulation at high altitude within the lungs are associated with changes in airway responses to methacholine or exercise. Fourteen healthy subjects were studied at 4,559 and at 120 m above sea level. At high altitude, both static and dynamic lung compliances and respiratory reactance at 5 Hz significantly decreased, suggestive of interstitial pulmonary edema. Resting minute ventilation significantly increased by approximately 30%. Compared with sea level, inhalation of methacholine at high altitude caused a similar reduction of partial forced expiratory flow but less reduction of maximal forced expiratory flow, less increments of pulmonary resistance and respiratory resistance at 5 Hz, and similar effects of deep breath on pulmonary and respiratory resistance. During maximal incremental exercise at high altitude, partial forced expiratory flow gradually increased with the increase in minute ventilation similarly to sea level but both achieved higher values at peak exercise. In conclusion, airway responsiveness to methacholine at high altitude is well preserved despite the occurrence of interstitial pulmonary edema. We suggest that this may be the result of the increase in resting minute ventilation opposing the effects and/or the development of airway smooth muscle force, reduced gas density, and well preserved airway-to-parenchyma interdependence.
Keywords AcclimatizationAdultAirway Resistance/physiologyAltitudeBlood Volume/physiologyBronchi/drug effects/physiologyExercise/physiologyExercise TestForced Expiratory Flow Rates/physiologyHumansLung/drug effects/physiologyLung Compliance/physiologyLung Volume MeasurementsMaleMethacholine Chloride/pharmacologyMiddle AgedMuscarinic Agonists/pharmacologyRespiratory Function TestsRespiratory Mechanics/drug effectsTidal Volume/physiology
PMID: 19940099
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Research group Groupe Kayser Bengt (médecine du sport) (306)
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PELLEGRINO, Riccardo et al. Airway responses to methacholine and exercise at high altitude in healthy lowlanders. In: Journal of Applied Physiology, 2010, vol. 108, n° 2, p. 256-65. doi: 10.1152/japplphysiol.00677.2009 https://archive-ouverte.unige.ch/unige:24885

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Deposited on : 2013-01-02

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