title: Responses to sulfur dioxide and exercise by medication-dependent asthmatics: effect of varying medication levels.
abstract: Twenty-one volunteers with moderate to severe asthma were exposed to sulfur dioxide (SO2) at concentrations of 0 (control), 0.3, and 0.6 ppm in each of three medication states: (1) low (much of their usual asthma medication withheld), (2) normal (each subject on his own usual medication schedule), and (3) high (usual medication supplemented by inhaled metaproterenol before exposure). Theophylline, the medication usually taken by subjects, was often supplemented by beta-adrenergics. Exposures were for 10 min and were accompanied by continuous heavy exercise (ventilation approximately 50 l/min). Lung function and symptoms were measured before and after exposure. With normal medication, symptomatic bronchoconstriction occurred with exercise and was exacerbated by 0.6 ppm SO2, as reported for mildly unmedicated asthmatics studied previously. Both baseline and post-exposure lung function were noticeably worse in the low-medication state. High medication improved baseline lung function and prevented most bronchoconstrictive effects of SO2/exercise. High medication also increased heart rate and apparently induced tremor or nervousness in some individuals.
authors.affiliation: Environmental Health Service, Rancho Los Amigos Medical Center, University of Southern California, Downey.
authors.forename: W S
authors.initials: WS
authors.lastname: Linn
authors.forename: D A
authors.initials: DA
authors.lastname: Shamoo
authors.forename: R C
authors.initials: RC
authors.lastname: Peng
authors.forename: K W
authors.initials: KW
authors.lastname: Clark
authors.forename: E L
authors.initials: EL
authors.lastname: Avol
authors.forename: J D
authors.initials: JD
authors.lastname: Hackney
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D015444:Exercise / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D009921:Metaproterenol / Q000008:administration & dosage; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects; D013147:Spirometry; D013458:Sulfur Dioxide / Q000008:administration & dosage / Q000494:pharmacology*; D013806:Theophylline / Q000008:administration & dosage* / Q000097:blood
chemical_list: D000319:Adrenergic beta-Antagonists; D001993:Bronchodilator Agents; D013458:Sulfur Dioxide; D009921:Metaproterenol; D013806:Theophylline