[Hering and Breuer reflexes in kittens in the early stages of postnatal ontogeny].

In 16 one to twelve-day old decerebrate kittens with intact nn. vagi, the reflex responses to trachea occlusion and alteration of the lung volume were studied. The EMGs of diaphragm and intercostal muscles were recorded as well as the tidal volume and the intratracheal pressure. The character of responses to above stimuli is similar in kittens and in adult cats. The trachea occlusion induces a greater elongation of expiration in kittens. Both in newborn and adult cats there is no obvious difference in intensity of expiratory-facilitating reflex in response to lung inflation. The threshold of inspiratory-exciting reflex in response to augmentation of the lung volume is relatively high in kittens. This reflex as well as the reflex to the lung collapse can be less regularly induced than in adults. It can be assumed that the sensitivity of bulbar respiratory center to impulses from the lung mechanoreceptors is relatively high in newborn animals.