Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was aimed at determining the role of carotid bodies in the initiation and maintenance of oral breathing during nasal obstruction. We have previously shown in sheep that oral breathing during nasal obstruction was less effective in the neonate than in older lambs or adults. We considered it possible that the reduced response of the neonate was due to immaturity of carotid body chemoreceptors. Respiratory and blood gas responses to nasal obstruction were determined in 5 neonatal lambs, 6 older lambs and 6 adult ewes before and after surgically denervating the carotid bodies. Denervations were performed at 4.2 +/- 0.9 days after birth in the neonatal lambs and at 41.5 +/- 2.5 days in the older lambs. Carotid body denervation led to hypoxia, hypercapnia and acidaemia in lambs and ewes during unobstructed nasal breathing, and, in response to nasal obstruction, delayed the onset of oral breathing so that it occurred at a greater degree of hypoxia. Following carotid body denervation the degree of hypercapnia and acidaemia during nasal obstruction was greater in lambs than in ewes. We conclude that the carotid bodies in lambs and ewes play an important role in the regulation of normal blood gases and pH, and in the establishment and effectiveness of oral breathing during nasal obstruction.
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PMID:The role of carotid bodies in the establishment of oral breathing during nasal obstruction in lambs and ewes. 211 63

Carotid body denervation (CBD) in neonatal goats and piglets results in minimal irregular breathing and no fatalities. Redundancy and/or plasticity of peripheral chemosensitivity and a relatively mature ventilatory control system at birth may contribute to the paucity of CBD effects in these species. In the present study, we tested the hypothesis that CBD mortality would be greater in neonates of a less mature species such as the rat. We found that the mortality in rats denervated at 2-3 and 7-8 days of age was significantly higher (P < 0.05) than in sham-CBD rats. In all surviving rats, pulmonary ventilation during hypoxia was lower in CBD than in sham operated rats 2 days after denervation. In surviving rats denervated during the 7th and 8th postnatal days, there was also reduced weight gain and pulmonary ventilation during eupnea, including apneas up to 20 s in duration. However, the effects of CBD were compensated within 3 wk after denervation. Local injections of NaCN indicated that aortic chemoreceptors might have been one of the sites of recovery of peripheral chemosensitivity. We concluded that CBD has higher mortality in newborn rats than in other mammals, possibly because of the relative immaturity of these animals at birth. Nonetheless, in survivors there was enough redundancy and plasticity in the control of breathing to eventually compensate for the consequences of CBD.
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PMID:Mortality after carotid body denervation in rats. 1150 29