Cough and bronchial constriction

Abstract

Result on experimental research about bronchioconstriction in cough are exposed. It is concluded that tracheal stimulation which produces cough always causes a certain degree of bron- chial constriction. This conclusión lies on a experimental data series, mainly on resistance measures. Comparisons between cough under control conditions and after atropine with breathing at rest of the same animal evidences that in control*s cough a remarkable increase of resistance that is absent in after atro­ pine provoked cough is produced. It is proved that tracheal stimulation increases resistance in inspiration as well as in expiration and that bronchiolitics prevent this effect. On expiratory resistance it is possible to distinguish two phases : at the beginning of resistance increase, when acceleration of c-x- piratorj’ outflow maximizes, influence of bronchioconstriction is evídent; in the final pha.se, concurring to máximum positive pleural pressure, increases of intrathoracic pressure passively prevails.

Studying codeine influence on bronchioconstriction provokedby tracheal stimulation it is seen that no influences or increases rcsistance but never decreases it.

Administration of bronchiolitics — atropin or isopropiladre- naline — strenght codeine effectiveness. These results are- in- terpretcd in the sense that bronchioconstriction produced by tracheal stimulation is factor of excitation of the expiratory center activity. And suppressing this cause of excitation, de­ crease of antitussive doses necessary to suppress cough is obtained.

Possible influence of narcotine is experimentally studied on bronchioconstriction produced as a response to trachealexcitation in dogs. According to diagrams obtained in cough (figure la), drugs does not appear to have any effect on bron- chial constriction. After narcotine injection in guinea pig — measuring expired air volume in controlled breathing — bron- chiodilation is not appreciated. Instead remarkable constric­ tion effect has been observed in some experiences. Influences on histamine or acetilcholine constriction in this experimental conditions is doubtful and does not permit certainly conclusions.