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[Central chemoreceptors and sudden infant death syndrome].

INTRODUCTION
Carbon dioxide partial pressure and pH in the extracellular compartment are the most powerful signals regulating respiration. Central chemoreceptors (QC) undergo the stimulating effect of CO2 and pH upon respiration.


AIMS
This review tries to provide an actual envision of the progress in the knowledgement on central chemoreception. It also tries to highlight the importance of the alterations in the chemoreception mechanism as a cause of sudden infant death syndrome (SIDS).


DEVELOPMENT
Central chemoreceptors respond to acid-base imbalance acting on neurons that give rise to the central breathing pattern and have the ability to change the respiratory rate, which is normally needed to restore the normal values of acid-base status. QC are widely distributed in the brain stem, however QC neurons in the ventral surface of the medulla like to be the main relays for ventilatory responses after acid-base stimulation.


CONCLUSIONS
It has been shown that QC are sensitive to pH and CO2 as in vivo as in vitro conditions, most of them being serotonin immunopositive, a neurotransmitter with known effects on breathing pattern. By other side, alterations of central chemoreception have been associated to pathologies like congenital hypoventilatory syndrome or SIDS. Interestingly, the post mortem exams of the brain of infants dead because these syndromes have showed anomalies of serotonergic receptor located in regions containing QC neurons and in others related with cardiorespiratory integration.