[Age changes in the respiratory cycle and pulmonary ventilation in kittens before and after vagotomy].

Studies have been made on the structure of respiratory period, the volume of pulmonary ventilation in decerebrated kittens during their first month of postnatal development. In most of the kittens respiration rate decreases with age, although in some of the animals it remained high. In newborn kittens, the afferentation from pulmonary mechanoreceptors is more significant for the limitation of the duration of expiration (TE) than that of inspiration (TI). Respiration rate in vagotomized kittens increases with age. The maturation of central mechanisms controlling the change of inspiration by expiration and the change of expiration by inspiration follows different patterns. After vagotomy, TI undergoes insignificant changes within the first 3 weeks, increasing on further development of the animals. High value of TE in these kittens results from poor activity of the central mechanisms which limit expiration. Intensive development of these mechanisms is observed from the 9th to the 18th day. After vagotomy, the decrease in respiration rate is not always compensated by the increase in respiration volume, which may account for the decrease in pulmonary ventilation.