Pattern and mechanism of airway response to hypocapnia in normal subjects. 1979

C F O'Cain, and M J Hensley, and E R McFadden, and R H Ingram

We examined the bronchoconstriction produced by airway hypocapnia in normal subjects. Maximal expiratory flow at 25% vital capacity on partial expiratory flow-volume (PEFV) curves fell during hypocapnia both on air and on an 80% helium- 20% oxygen mixture. Density dependence also fell, suggesting predominantly small airway constriction. The changes seen on PEFV curves were not found on maximal expiratory flow-volume curves, indicating the inhalation to total lung capacity substantially reversed the constriction. Pretreatment with a beta-sympathomimetic agent blocked the response, whereas atropine pretreatment did not, suggesting that hypocapnia affects airway smooth muscle directly, not via cholinergic efferents.

UI MeSH Term Description Entries
D007528 Isoetharine Adrenergic beta-2 agonist used as bronchodilator for emphysema, bronchitis and asthma. Etyprenalinum,Bronkometer,Isoetarin,Isoetharine Mesylate,Mesylate, Isoetharine
D008297 Male Males
D008448 Maximal Expiratory Flow Rate The airflow rate measured during the first liter expired after the first 200 ml have been exhausted during a FORCED VITAL CAPACITY determination. Common abbreviations are MEFR, FEF 200-1200, and FEF 0.2-1.2. Forced Expiratory Flow 0.2-1.2,Forced Expiratory Flow 200-1200,Flow Rate, Maximal Expiratory,MEFR,Forced Expiratory Flow 0.2 1.2,Forced Expiratory Flow 200 1200
D010100 Oxygen An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration. Dioxygen,Oxygen-16,Oxygen 16
D012120 Respiration Disorders Diseases of the respiratory system in general or unspecified or for a specific respiratory disease not available. Disorder, Respiration,Disorders, Respiration,Respiration Disorder
D001980 Bronchi The larger air passages of the lungs arising from the terminal bifurcation of the TRACHEA. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into BRONCHIOLES and PULMONARY ALVEOLI. Primary Bronchi,Primary Bronchus,Secondary Bronchi,Secondary Bronchus,Tertiary Bronchi,Tertiary Bronchus,Bronchi, Primary,Bronchi, Secondary,Bronchi, Tertiary,Bronchus,Bronchus, Primary,Bronchus, Secondary,Bronchus, Tertiary
D002245 Carbon Dioxide A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals. Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D003251 Constriction, Pathologic The condition of an anatomical structure's being constricted beyond normal dimensions. Stenosis,Stricture,Constriction, Pathological,Pathologic Constriction,Constrictions, Pathologic,Pathologic Constrictions,Pathological Constriction,Stenoses,Strictures
D005540 Forced Expiratory Flow Rates The rate of airflow measured during a FORCED VITAL CAPACITY determination. Expiratory Forced Flow Rates,Flow Rates, Expiratory Forced,Flow Rates, Forced Expiratory
D006371 Helium A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics. Helium-4,Helium 4

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