Origin of the chloride current in olfactory transduction.
In the cilia of amphibian olfactory receptor neurons, odorants elicit a receptor current that has two components: a cationic current through cAMP-gated channels and a Cl- current. Here, a cascade of ciliary currents that accounts for the total receptor current is demonstrated. In isolated olfactory cilia, cAMP sequentially activates two currents. The first is a primary cationic current through channels directly gated by cAMP. Part of this current is carried by Ca2+, which in turn activates a Cl- current. This secondary current is eliminated by the presence of Cl- channel inhibitors, replacement of Cl- with methanesulfonate-, removal of external Ca2+, or blockers of the cAMP-gated cationic channels. When cytoplasmic Ca2+ buffering is low, small cationic currents can activate Cl- currents that are 20 times larger.
Kleene
S J
SJ
Department of Anatomy and Cell Biology, University of Cincinnati, Ohio 45267-0521.
D000818:Animals; D002021:Buffers; D002118:Calcium / Q000494:pharmacology; D002412:Cations / Q000378:metabolism; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D002923:Cilia / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism; D004594:Electrophysiology; D015640:Ion Channel Gating; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D009833:Olfactory Pathways / Q000502:physiology*; D011894:Rana pipiens
D002021:Buffers; D002412:Cations; D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D000242:Cyclic AMP; D002118:Calcium