Nonselective cation channel activated by patch excision from lobster olfactory receptor neurons

Timothy S. McClintock, Barry W. Ache

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


A nonselective cation channel activated by patch excision was characterized in inside-out patches from spiny lobster olfactory receptor neurons. The channel, which was permeable to Na+, K+ and Cs+, had a conductance of 320 pS and was weakly voltage dependent in the presence of micromolar divalent cations. Millimolar internal divalent cations caused a voltage-and concentration-dependent block of Na+ permeation. Analysis of the voltage dependence indicated that the proportion of the membrane's electric field sensed by Mg2+ was >1, suggesting that the channel contains a multi-ion pore. Internal divalent cations also reduced the frequency of channel opening in a concentration-dependent, but not voltage-dependent, manner, indicating that different cation binding sites affect gating and conductance. While block of gating prevented determining if internal divalent cations permeate the channel, a channel highly permeable to external divalent cations was observed upon patch excision to the inside-out configuration. The monovalent and divalent cation conductances shared activation by patch excision, weak voltage dependence, and steady-state activity, suggesting that they are the same channel. These data extend our understanding of this type of channel by demonstrating permeation by monovalent cations, detailing Mg2+ block of Na- permeation, and demonstrating the channel's presence in arthropods.

Original languageEnglish
Pages (from-to)115-122
Number of pages8
JournalThe Journal of Membrane Biology
Issue number2
StatePublished - Feb 1990


  • channel blockers
  • ion channels
  • lobster
  • olfaction
  • sensory cells

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology


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