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This Article Full Text Full Text (PDF) All Versions of this Article: 586/8/2043    most recent jphysiol.2008.150870v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Guyenet, P. G. Articles by Bayliss, D. A. PubMed PubMed Citation Articles by Guyenet, P. G. Articles by Bayliss, D. A. Related Collections Review articles Neuroscience

¹ Department of Pharmacology, University of Virginia, Charlottesville, VA, USA

The ‘distributed chemoreception theory’ attributes the central chemoreflex (the stimulation of breathing by CNS acidification) to the cumulative effects of pH on multiple classes of respiratory neurons as well as on their tonic sources of drive. Opinions differ as to how many classes of pH-sensitive neurons contribute to the central chemoreflex but the number of candidates is high and growing fast. The ‘specialized chemoreceptor theory’, endorsed here, attributes the chemoreflex to a limited number of specialized neurons. These neurons (the central chemoreceptors) would drive a respiratory pattern generator that is not or minimally activated by acidification. In this review we first describe the properties of the retrotrapezoid nucleus (RTN) and argue that this nucleus may contain the most important central chemoreceptors. Next, we subject the assumptions that underlie the distributed chemoreception theory to a critical analysis. We propose several explanations for the apparent contradiction between the two competing theories of central chemoreception. We attribute much of the current controversy to premature extrapolations of the effects of acidification on neurons recorded in vitro (chemosensitivity) and to a semantic confusion between chemosensitivity and chemoreception (the mechanism by which CO₂ or pH activates breathing in vivo).

(Received 8 January 2008; accepted after revision 11 February 2008; first published online 28 February 2008)
Corresponding author P. G. Guyenet: University of Virginia Health System, P.O. Box 800735, 1300 Jefferson Park Avenue, Charlottesville, VA 22908-0735, USA. Email: pgg{at}virginia.edu