Postnatal maturation of carotid chemoreceptor responses to 02

2391, 1993.-This study aimed to characterize neural re-sponses of the carotid chemoreceptors of the maturing cat to natural stimuli and to determine the time course of carotid chemoreceptor development from the neonatal period to adult-hood. Carotid sinus nerve (CSN) responses to 0, and CO, were studied in cats at 1,4, and 8 wk of age and in adult cats (n = 6-at each age). Pentobarbital sodium-anesthetized cats were ex-posed to three levels of 0, (arterial PO, = 40-45, 80-90, and>300 Torr) at five levels of arterial PCO ~ (22,35,48,63, and 75 Torr) while the moving average of whole nerve output from the CSN was recorded. Ganglioglomerular nerves were sectioned. All cats at every age increased CSN activity during hypoxia. However, the CSN response to hypoxia was not sustained in some immature cats. Of the cats that sustained CSN activity during hypoxia, four of the six 1-wk-old cats showed a biphasic pattern of response, with an initial overshoot followed by