Effect of circadian rhythm on bronchomotor tone after deep inspiration in normal and in asthmatic subjects.
Bronchomotor tone after deep inspiration and bronchial responsiveness to methacholine were studied at 4:00 A.M. and 4:00 P.M. in 14 normal and 13 asthmatic subjects. Bronchomotor tone was assessed with respiratory resistance (Rrs) measured by the forced oscillation method. Bronchial responsiveness to methacholine and baseline Rrs were higher at 4:00 A.M. than at 4:00 P.M. in both normal and asthmatic subjects (p less than 0.01). The difference in methacholine threshold between 4:00 P.M. and 4:00 A.M. In asthmatics was similar to that in normal subjects. Immediately after deep inspiration, Rrs decreased more at 4:00 A.M. than at 4:00 P.M. In normal subjects. In contrast, asthmatic subjects showed a significantly greater immediate increase in Rrs after deep inspiration at 4:00 A.M. than at 4:00 P.M. It is suggested that the bronchoconstrictive effect after deep inspiration is a distinguishing characteristic of asthmatics.
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000502:physiology* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D002395:Catecholamines / Q000097:blood; D002940:Circadian Rhythm; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D008875:Middle Aged; D012119:Respiration
D002395:Catecholamines; D008688:Methacholine Compounds; D016210:Methacholine Chloride