The influence of a minimal surgical transection around the trachea on ACH- and allergen-induced bronchoconstriction was studied in a series of 21 cats. A significant smaller bronchoconstriction was observed after surgical transection around the trachea. The trachea isolation itself induced a smaller nonsignificant bronchoconstrictive response. This diminished response of the airways after this surgical intervention assumes an interruption of syncytial connections, which alters the response to bronchoconstricting stimuli of the whole bronchial system. The exact role of these syncytial connections has yet to be clarified