Odorant suppression of delayed rectifier potassium current in newt olfactory receptor cells.
Effects of odorants on a delayed rectifier potassium current (IK) in newt olfactory receptor cells (ORCs) were investigated using the whole-cell version of the patch-clamp technique. Under voltage clamp, odorants (amyl acetate, limonene and acetophenone) reversibly suppressed I(K) without shifting its I-V curve. An amyl acetate puff completely suppressed I(K) induced by the first step pulse of repetitive depolarizations, suggesting that binding of an odorant molecule to the open channel is not required to block the channel. Although it is known that odorants suppress Na+ and Ca2+ currents (I(Na), I(Ca)) by shifting their inactivation curves to a negative voltage, odorants did not shift the inactivation curve of I(K) significantly. This suggests that odorants suppress I(K) without changing its voltage dependence. Therefore, the blocking mechanisms by odorants of I(K) in ORCs are different from those of I(Na) and I(Ca).
Kawai
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Department of Information Physiology, National Institute for Physiological Sciences, Okazaki, Japan. fusao@retina.anatomy.upenn.edu
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D053138:Cyclohexenes; D000077222:Limonene; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009812:Odorants; D018034:Olfactory Receptor Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D000439:Pentanols / Q000494:pharmacology; D017319:Photosensitizing Agents / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology*; D012455:Salamandridae; D013729:Terpenes / Q000494:pharmacology; D013997:Time Factors
D000098:Acetophenones; D002273:Carcinogens; D053138:Cyclohexenes; D000439:Pentanols; D017319:Photosensitizing Agents; D015221:Potassium Channels; D013729:Terpenes; C005716:amyl acetate; D000077222:Limonene; C038699:acetophenone