EN
Gromysz H., Karczewski W. A., Kukwa A., Jernajczyk U.: Breuer-Hering reflexes in ketamine-induced apneustic breathing in the rabbit. Acta Physiol. Pol. The effects of ketamine on the activities of the mylohyoid nerve (a branch of the Vth nerve) and of both phrenic nerves were investigated in rabbits anaesthetized with halothane, paralyzed and artificially ventilated. Intravenous administration of ketamine elicited a marked prolongation of the phrenic inspiratory discharge [without] not significantly affecting its amplitude) and a depression of the mylohyoid expiratory activity. An elimination of the volume-related input from the lungs (“no inflation manoeuvre” or deflation) elicited under these conditions typical apneustic pattern of breathing. The response to tracheal occlusion at peak-inspiration was “classical”. We conclude that ketamine inhibits the Vth nerve motor nucleus which is not only an important component of the central inspiratory-inhibitory neurones but also a “relay station” between the vagal and the central inspiratory “off-switch” mechanisms.