[Nervous control of bronchial circulation in pigs: application to the airway stimulation]

Vascular responses in airways were studied in an anesthetized pig model. Nervous control of bronchial mucosa blood flow was found to involve mainly the non-adrenergic, non-cholinergic (NANC) system (activation of afferent C-fibers) and the sympathetic system. Nervous control of tracheal and laryngeal vascularization involved the cholinergic and non-cholinergic parasympathetic system and the sympathetic system. Exposure of airways to irritants was followed by vasodilatation in the tracheobronchial mucosa, partly as a result of activation of afferent C-fibers. In sensitized animals, respiratory challenge with the specific allergen produced activation of the NANC system with antidromic vasodilatation in the mucosa. This response can be likened to the "axon reflex" seen in skin. Activation of airway autonomic nerves thus was found to be a central step in the genesis of inflammatory reactions in the lungs.