Carotid body postnatal maturation

Bureau MA, Lamarche J, Foulon P, Dalle D. Postnatal maturation of respiration in intact and carotid body-chemodenervated lambs. J Appl Physiol 1985 59 869-874. Bureau MA, Lamarche J, Foulon P, Dalle D. The ventilatory response to h poxia in the newborn lamb after carotid body denervation. Respir Physiol 1985 60 109-119. Hofer MA. Sleep-wake state organization in infant rats with episodic respiratory disturbance following sinoaortic denervation. Sleep 1985 8 40 8. 

Postnatal carotid chemoreeeptor maturation and mechanisms of development were recently reviewed (35) and are discussed elsewhere in this volume. This chapter will therefore focus on postnatal developmental changes occurring at the level of the type I or glomus cells, believed to be the 02-sensing element in the carotid body. 

In every species studied to date, the carotid chemoreceptor response to hypoxia increases with postnatal age. In in vitro carotid body preparations, the peak nerve discharge in response to a potent hypoxia stimulus increases about fourfold in neonatal rats during the first month, with most of that change occurring by 2 weeks (10,12,45) (Fig. 2). Similar patterns of postnatal maturation of carotid sinus nerve... 

Tyrosine hydroxylase (TH), a key eirzyme in DA synthesis, also changes during development. An early study of rat carotid body development showed that the level of TH mRNA expression was greatest in the term fetus, decreased 60% by 10 hr postnatal age, and declined another 20% by 4-7 days (54). Similarly, a recent study reported that the level of rat carotid body TH mRNA expression was greatest at birth, significantly decreased by 48 hr postnatal age, and remained decreased at 14 and 21 postnatal days (55). Thus, consistent with the above studies on DA levels, TH mRNA drops rapidly within hours of birth and charrges little during the time frame of carotid sinus nerve activity maturation. 

Bureau MA, Lamarche J, Foulon P, Dalle D. Postnatal maturation of respiration in intact and carotid body-chemodenervated lambs. J Appl Physiol 1985 59(3) 869-874. 

Bamford OS, Stemi LM, Wasicko MJ, Montrose MH, Carroll JL. Postnatal maturation of carotid body and type I cell chemoreception in the rat. Am J Physiol 1999 276(5 Pt 1) L875-L884. 

The potential for maturational changes in the sensitivity of a putative O2 sensor does not, of course, exclude the possibility of other maturational changes occurring at sites more distal to the sensor. Indeed, a significant body of evidence has been gathered to demonstrate a postnatal elevation in catecholamine, specifically dopamine, mRNA levels in carotid body and pelrosal ganglion tissue (86,87). Additionally, the amount of catecholamine released with hypoxia (88,89) but not with elevated extracellular K concentration (89) increases with postnatal age. 

Bolle T, Lauweryns JM, Van Lommel A. Postnatal maturation of neuroepithelial bodies and carotid body innervation a quantitative investigation in the rabbit. J Neurocytol 2000 29 241-248. 

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