A model of CO2 chemotransduction in avian intrapulmonary chemoreceptors

Steven C Hempleman, T. A. Rodriguez

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Intrapulmonary chemoreceptors (IPC) are exquisitely sensitive to steady and dynamically changing CO2 levels in avian lungs, but the mechanism of chemotransduction remains unknown. We sought a model that could explain the following experimental data: (1) hydratable acidic gases like CO2 and SO2 inhibit IPC discharge; (2) membrane permeant carbonic anhydrase (CA) inhibitors block CO2 response and produce near maximal IPC discharge rates (fIPC) at all CO2 levels; (3) chronic acclimatization to elevated CO2 increases fIPC (and body fluid pH) at any given PCO2; (4) chronic metabolic acidosis reduces fIPC (and body fluid pH) at most PCO2; (5) acute metabolic acidosis or alkalosis (which may not alter intracellular pHi) has little effect on fIPC. We propose the following model of IPC chemotransduction: When CO2 is low, IPC are excited by high pHi which may directly decrease a repolarizing membrane ton channel conductance (eg. for K+), or increase a depolarizing ion channel conductance (eg. for Na+). This excitation should rapidly decrease when pHi falls with elevated PCO2. We also propose a continuous active transport of H+ out of IPC endings with first order kinetics, which gives rise to adaptation with dynamically changing CO2 signals, and near maximal IPC discharge at all PCO2 levels when CA is inhibited (pHi always high). This model may be tested with ion channel blockers and active transport inhibitors.

Original languageEnglish (US)
JournalFASEB Journal
Volume11
Issue number3
StatePublished - 1997

Fingerprint

chemoreceptors
Ion Channels
Active Biological Transport
Body fluids
carbon dioxide
Body Fluids
Acidosis
Carbonic Anhydrase Inhibitors
Alkalosis
Carbonic Anhydrases
Acclimatization
active transport
body fluids
carbonate dehydratase
ion channels
acidosis
Gases
Membranes
Lung
Kinetics

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

A model of CO2 chemotransduction in avian intrapulmonary chemoreceptors. / Hempleman, Steven C; Rodriguez, T. A.

In: FASEB Journal, Vol. 11, No. 3, 1997.

Research output: Contribution to journalArticle

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