Sensitivity at the Cellular Level

Postnatal Maturation of the Carotid Chemoreceptor O2 Sensitivity at the Cellular Level 

University of Arkansas for Medical Sciences and Arkansas Children s Hospital Little Rock, Arkansas, U.S.A. 

Perhaps surprisingly, given their importance in the developing infant, the carotid chemoreceptors have minimal sensitivity to hypoxia at birth and become more sensitive over the first few days or weeks of life (10-16). Increasing hypoxia sensitivity of the arterial chemoreceptors after birth is termed resetting, and it occurs in both carotid and aortic chemoreceptors (17). Carotid chemoreceptor resetting appears to be modulated by the 4-fold rise in arterial O2 tension that occurs at birth (18-22), raising the possibility that peri- and postnatal hypoxia may impair carotid chemoreceptor development. In addition, perinatal hyperoxia causes 

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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. 

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