Effect of Deep Inspiration on Maximum Expiratory Flow (V_max) Depends on Basal Bronchomotor Tone in Young Healthy Females

Abstract

The relationship between the effect of deep inspiration on V_max and basal bronchomotor tone was studied by partial and maximum expiratory flow-volume curve in 16 young healthy females (20-21 years old).
Effect of deep inspiration on V_max (DI index; (PEF₂₅-MEF₂₅)/PEF₂₅) significantly related to percent increase in PEF₂₅ not only by inhalation of ipratropium bromide (r=-0.81, p<0.0002) but also by inhalation of salbutamol (r=-0.62, p<0.01). Furthermore, day to day variation of DI index significantly related to day to day variation of PEF₂₅ (r=0.68, p<0.005) but not to that of MEF₂₅.
These findings suggest that the bronchodilating effect of deep inspiration in young healthy females may depend on intensity of basal bronchomotor tone caused by tonic vagal nerve activity.