title: Investigation of nasal CO₂ receptor transduction mechanisms in wild-type and GC-D knockout mice.
abstract: The main olfactory system of mice contains a small subset of olfactory sensory neurons (OSNs) that are stimulated by CO₂. The objective of this study was to record olfactory receptor responses to a range of CO₂ concentrations to further elucidate steps in the proposed CO₂ transduction pathway in mice. Electro-olfactograms (EOGs) were recorded before and after inhibiting specific steps in the CO₂ transduction pathway with topically applied inhibitors. Inhibition of extracellular carbonic anhydrase (CA) did not significantly affect EOG responses to CO₂ but did decrease EOG responses to several control odorants. Inhibition of intracellular CA or cyclic nucleotide-gated channels attenuated EOG responses to CO₂, confirming the role of these components in CO₂ sensing in mice. We also show that, like canonical OSNs, CO₂-sensitive OSNs depend on Ca²⁺-activated Cl⁻ channels for depolarization of receptor neurons. Lastly, we found that guanylyl cyclase-D knockout mice were still able to respond to CO₂, indicating that other pathways may exist for the detection of low concentrations of nasal CO₂. We discuss these findings as they relate to previous studies on CO₂-sensitive OSNs in mice and other animals.
authors.affiliation: Department of Biology, Allegheny College, 520 North Main Street, Meadville, PA 16335, USA. lcoates@allegheny.edu.
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Kenemuth
authors.forename: Shane P
authors.initials: SP
authors.lastname: Hennessy
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Hanson
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Hensler
authors.forename: E Lee
authors.initials: EL
authors.lastname: Coates
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D018118:Chloride Channels / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000378:metabolism; D055724:Electrophysiological Phenomena; D005260:Female; D006162:Guanylate Cyclase / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009297:Nasal Mucosa / Q000187:drug effects* / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000378:metabolism; D000439:Pentanols / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012903:Smell / Q000502:physiology
chemical_list: D018118:Chloride Channels; D054815:Cyclic Nucleotide-Gated Cation Channels; D000439:Pentanols; D011956:Receptors, Cell Surface; D002245:Carbon Dioxide; C005716:amyl acetate; D006162:Guanylate Cyclase; C484774:Gucy2d protein, mouse
keywords: CNG channels; cGMP; carbonic anhydrase; chloride channels; olfaction; olfactory sensory neurons