CO 2 transduction mechanisms in avian intrapulmonary chemoreceptors: Experiments and models

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Abstract

Intrapulmonary chemoreceptors (IPC) are neurons that sense tonic and phasic CO 2 stimuli in the lungs of birds and diapsid reptiles. IPC are different from most other vertebrate respiratory CO 2 receptors because: (1) they are stimulated by low P CO2 and inhibited by high P CO2, (2) they have extremely rapid response characteristics, (3) their CO 2 sensitivity is nearly abolished by intracellular inhibitors of carbonic anhydrase, and (4) their CO 2 sensitivity is strongly depressed by inhibiting Na +/H + antiport exchange. Experimental evidence suggests that IPC respond to intracellular pH, not CO 2 directly, and that intracellular pH and IPC discharge are determined by a kinetic balance between CO 2 hydration/dehydration rates, transmembrane acid/base exchange rates, and intracellular buffering. We review experimental evidence for and against various mechanisms of IPC CO 2 chemotransduction, present a conceptual and mathematical model of the proposed mechanisms, and compare this model to CO 2 transduction in other respiratory chemoreceptors.

Original languageEnglish (US)
Pages (from-to)203-214
Number of pages12
JournalRespiratory Physiology and Neurobiology
Volume144
Issue number2-3 SPEC. ISS.
DOIs
StatePublished - Dec 15 2004

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Keywords

  • Acid-base
  • Carbonic anhydrase
  • Chemical kinetics
  • Cl /HCO
  • Control of breathing
  • Differential equations
  • Exchanger
  • Intracellular pH
  • Na /H

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Neuroscience(all)

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