Distilled water aerosol causes bronchoconstriction in Basenji-greyhound (BG) dogs

Inhalation of ultrasonically nebulized distilled water aerosol causes bronchoconstriction in people with asthma, but not in normal healthy subjects. However, the mechanism is unknown. BG dogs show increased bronchomotor responses to inhaled bronchoactive drugs similar to asthmatics (J. Appl. Physiol. 49:953-957, 1980). Therefore, we wanted to determine whether these dogs also respond to osmolar challenge. We report an increased bronchomotor response to inhalation of distilled water into two BG dogs. Distilled water was delivered through a Mistogen ultrasonic nebulizer (mass median aerodynamic diameter = 6.3 μm) at a flow rate of 3 ml/min for 1 min, 5 min, or 10 min. In one BG dog, R(L) increased from 1.0 cm/L/s (baseline) to 2.6 cm/L/s at 1 min, and 3.4 cm/L/s at 6 min and from 1.9 cm/L/s (baseline) to 11.9 cm/L/s at 10 min after distilled water aerosol; in another dog, R(L) increased from 1.9 cm/L/s (baseline) to 15.2 cm/L/s at 10 min. In contrast, 10 min after distilled water aerosol, R(L) = cm/L/s in two mongrel dogs which did not differ significantly from baseline R(L) (1.5 cm/L/s). These studies provide further evidence that the airway smooth muscle responses of BG dogs mimic those of asthmatic humans.