Characterization of voltage- and Ca(2+)-activated K+ channels in squid olfactory receptor neurons.
We performed whole-cell voltage-clamp experiments on isolated olfactory neurons from the squid Lolliguncula brevis. Total outward currents were composed of three identifiable K+ currents: a delayed rectifier K+ current that showed slow inactivation and was sensitive to 5 mmol l-1 tetraethylammonium; a rapidly inactivating, 4-aminopyridine (4-AP)-sensitive, A-type K+ current and a Ca(2+)-sensitive K+ current that was blocked by 200 nmol l-1 charybdotoxin and 10 mmol l-1 Cd2+ but was insensitive to apamin. The proportion of each current type varied from cell to cell, suggesting that responses to a given odorant would depend of the complement of channels present. The kinetics of the K+ currents were affected by temperature, with Q10 values ranging from 2 to 6. The identification and characterization of these K+ currents will greatly aid our understanding of action potential generation in these cells and will facilitate modelling of how odor responses are transduced and coded in squid olfactory receptor neurons.
Lucero
M T
MT
Department of Physiology, School of Medicine, University of Utah, Salt Lake City 84108, USA.
Chen
N
N
D000818:Animals; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D049832:Decapodiformes / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000032:analysis* / Q000502:physiology
D015221:Potassium Channels; D002118:Calcium