Dopamine and 3,4-Dihydroxyphenylacetic Acid Concentrations in Rat Carotid Body:The Effects of Chronic Hypoxia and Hyperoxia from Birth

Abstract

Naeye (1974) reported that chronic hypoxaemia in newborn infants is often associated with respiratory disorders. It was further proposed that such hypoxaemia could be linked with the Sudden Infant Death Syndrome (SIDS). Dopamine (DA) is one of several neuroactive substances which are known to be present in the cells of the mammalian carotid body and which has been suggested to play a role in chemoreception. The content of DA in adult rat carotid body has been reported to change with exposure to hypoxia (Mills and Slotkin, 1975: Hanbauer and Hellstrom, 1978: Pallot and Barer, 1982: Barer and Pallot, 1984): also, the synthesis and release of the amine is increased in rabbit carotid bodies exposed to hypoxia in vitro (Fidone, Gonzalez and Yoshizaki, 1982). When the content of DA and its metabolite 3, 4-dihydroxyphenylacetic acid (Dopac) was compared in carotid bodies from fetal and newborn (<24 h old) lambs, it was found to increase dramatically at birth (Dawes et al., 1983). However, there was no significant change in DA or Dopac during the period of postnatal chemoreceptor resetting (Dawes et al., 1983). The significance of this change for chemoreception in the newborn remains to be defined. However, recently Perrin et al., (1984) reported that the carotid bodies of SIDS victims contained significantly higher concentrations of DA and noradrenaline than those of age-matched control infants. It was suggested that this indicates a neurochemical abnormality in carotid body function which may be associated with SIDS.