Mechanical stimulation of canine respiratory tract and nasal vascular and airway resistances.

Mechanical irritation of the upper airways (nose and larynx) decreased nasal vascular and airway resistances in anaesthetized dogs; the responses were probably due to dilatation of the nasal resistance and venous outflow blood vessels via stimulation of irritant receptors. Mechanical irritation of the lower airways (bronchi) increased nasal vascular resistance but decreased nasal airway resistance; the responses were probably due to constriction of nasal resistance and venous sinusoidal blood vessels via stimulation of cough receptors.