[Effect of bronchodilators on density dependence of expiratory flow-volume curves. An attempt to localize bronchodilators site of activity (author transl)].

In order to localize bronchodilators site of activity we studied the maximal expiratory flow-volume curves breathing air and 80 percent-20 percent helium-oxygen mixture in 11 normal and 23 asthmatic children. We measured delta Vmax. 60 percent TLC. delta Vmax. 45 percent TLC and VisoV. Half of the subjects received 400 gamma of fenoterol (beta2-sympathicomimetic), the other ones 200 gamma of SCH 1000 (synthetic atropine). Whatever the bronchodilator used, we found different types of response: 1 degree No modification in comparison with control period; 2 degree Increase of deltaVmax. with decrease of VisoV; 3 degree decrease of delta Vmax. with rise of VisoV. Thus we were unable to show a specific bronchodilator site of activity. However, in a few subjects, SCH 1000 principally acted on large airways whereas in some others fenoterol essentially acted on small airways.