title: Outward currents in olfactory receptor neurons activated by odorants and by elevation of cyclic AMP.
abstract: We studied the outward currents elicited by an odorous compound, isoamyl acetate, in isolated olfactory receptor neurons of the grass frog under whole-cell perforated-patch voltage-clamp recording. Odorant-induced outward currents were relatively rare, occurring in about 16% of the responding cells. Responses had smaller amplitudes and shorter time courses when compared to the more commonly found odorant-induced inward currents. There was a high correlation between odorant-induced outward current and responses evoked by either 8-(4-chlorophenylthio) adenosine 3':5'-cyclic monophosphate, a membrane-permeant cyclic adenosine monophosphate analog, or 3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor. The outward current responses to all three substances increased in amplitude when the membrane potential was more negative than -60 mV and decreased in amplitude when the membrane potential was more positive. Responses were still present when the potential was held at -100 mV, indicating that the responses are not the result of a potassium conductance. Removal of external calcium from the perfusion medium abolished the outward currents. Our results indicate that the odorant-induced outward current is a calcium-dependent event that may be mediated by cyclic adenosine monophosphate.
authors.affiliation: Department of Molecular and Cellular Physiology, University of Cincinnati, OH 45267-0576, USA. Raymund.Pun@uc.edu
authors.forename: Raymund Y K
authors.initials: RY
authors.lastname: Pun
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kleene
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000008:administration & dosage; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D000439:Pentanols / Q000494:pharmacology; D011894:Rana pipiens; D018035:Receptors, Odorant / Q000187:drug effects / Q000502:physiology*; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D000439:Pentanols; D018035:Receptors, Odorant; D013873:Thionucleotides; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine; C020377:isoamyl acetate