Ionic currents and ion channels of lobster olfactory receptor neurons

Timothy S. McClintock, Barry W. Ache

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The role of the soma of spiny lobster olfactory receptor cells in generating odor-evoked electrical signals was investigated by studying the ion channels and macroscopic currents of the soma. Four ionic currents; a tetrodotoxin-sensitive Na+ current, a Ca++ current, a Ca++-activated K+ current, and a delayed rectifier K+ current, were isolated by application of specific blocking agents. The Na+ and Ca++ currents began to activate at -40 to -30 mV, while the K+ currents began to activate at - 30 to - 20 mV. The size of the Na+ current was related to the presence of a remnant of a neurite, presumably an axon, and not to the size of the soma. No voltage-dependent inward currents were observed at potentials below those activating the Na+ current, suggesting that receptor potentials spread passively through the soma to generate action potentials in the axon of this cell. Steady-state inactivation of the Na+ current was half-maximal at -40 mV. Recovery from inactivation was a single exponential function that was half-maximal at 1.7 ms at room temperature. The K+ currents were much larger than the inward currents and probably underlie the outward rectification observed in this cell. The delayed rectifier K+ current was reduced by GTP-γ-S and AlF4, agents which activate GTP-binding proteins. The channels described were a 215-pS Ca++-activated K+ channel, a 9.7-pS delayed rectifier K+ channel, and a 35-pS voltage-independent Cl channel. The Cl channel provides a constant leak conductance that may be important in stabilizing the membrane potential of the cell.

Original languageEnglish
Pages (from-to)1085-1099
Number of pages15
JournalJournal of General Physiology
Volume94
Issue number6
DOIs
StatePublished - Dec 1 1989

ASJC Scopus subject areas

  • Physiology

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