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This Article Full Text Full Text (PDF) All Versions of this Article: 559/2/535    most recent jphysiol.2004.067611v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pun, R. Y. K. Articles by Kleene, S. J. Search for Related Content PubMed PubMed Citation Articles by Pun, R. Y. K. Articles by Kleene, S. J.

¹ Department of Molecular and Cellular Physiology
² Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati, Cincinnati, OH 45267, USA

The ability of a frog olfactory receptor neurone (ORN) to respond to odorous molecules depends on its resting membrane properties, including membrane resistance and potential. Quantification of these properties is difficult because of a shunt conductance at the membrane–pipette seal that is in parallel with the true membrane conductance. In physiological salines, the sum of these two conductances averaged 235 pS. We used ionic substitution and channel blockers to reduce the membrane conductance as much as possible. This yielded a lower limit for the membrane conductance of 158 pS. The upper limit of resting membrane resistance, then, is 6 G. The membrane is permeable to K⁺ and, to a lesser extent, other cations. No resting Cl^– conductance was detectable. Correcting measured zero-current potentials for distortion by the shunt suggests that the resting membrane potential is no more negative than –75 mV. The present results help to explain why frog ORNs are excitable at rest.

(Received 3 May 2004; accepted after revision 8 July 2004; first published online 22 July 2004)
Corresponding author R. Y. K. Pun: Department of Molecular and Cellular Physiology, University of Cincinnati, PO Box 670576, Cincinnati, OH 45267-0576, USA. Email: raymund.pun{at}uc.edu

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