[Influence of airway temperature and humidity of hyperventilation induced bronchoconstriction in rabbits]

It has been suggested that humidity and temperature of inspired air is important in determining the severity of hyperventilation induced bronchoconstriction (HIB). To investigate whether water loss or heat loss from airway plays more important role to induce HIB, we compared the effect of temperature and humidity of inspired air on HIB, in sensitized and non-sensitized rabbits. Inspired air containing 5% CO2 was conditioned to dry or humidified and to temperature of 9 degrees C or 25 degrees C during isocapnic hyperventilation. In sensitized rabbits, marked bronchoconstriction was observed when inspired air dry regardless of temperature. We conclude that 1) HIB is produced in sensitized rabbits and 2) humidity rather than temperature of inspired air is more important to induce HIB.