[Reflex effects of cough reflex on the tracheobronchial vascular tone (author's transl)]

In a previous paper, it was shown that the cough reflex was accompanied by a slight fall of systemic arterial pressure, tracheal constriction and tracheal vasodilation. In the present study, tracheobronchial muscular and vascular tones during the cough reflex were investigated using the blood perfused canine tracheal and bronchial preparations in situ. The cough reflex was elicited with electrical stimulation of the membraneous wall mucosa of the upper trachea. In the blood perfused tracheal preparation, a close intraarterial injection of atropine or bilateral vagotomy inhibited the tracheoconstriction but had no effect on the tracheal vasodilation during the cough reflex. In the blood perfused bronchial preparation, electrical stimulation of the upper tracheal mucosa induced bronchial constriction but not bronchial vasodilation. Lung inflation with air resulted in a bronchial vasodilation and which persisted even after a close intraarterial infusion of atropine and benzonatate and after bilateral vagotomy. These findings indicate that the tracheobronchial constriction response are primary reflex effects following coughing and the tracheobronchial vasodilation responses are secondary reflex effects induced by increase in internal pressure of the respiratory tract.