Transient and persistent tetrodotoxin-sensitive sodium currents in squid olfactory receptor neurons |
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Authors: | N. Chen M. T. Lucero |
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Affiliation: | (1) Department of Psychiatry, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3, CA;(2) Department of Physiology, School of Medicine, University of Utah, Salt Lake City, UT 84108, USA e-mail: Mary.Lucero@m.cc.utah.edu Tel.: +1-801-5855601; Fax: +1-801-5813476, US |
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Abstract: | Squid olfactory receptor neurons are primary bipolar sensory neurons capable of transducing water-born odorant signals into electrical impulses that are transmitted to the brain. In this study, we have identified and characterized the macroscopic properties of voltage-gated Na+ channels in olfactory receptor neurons from the squid Lolliguncula brevis. Using whole-cell voltage-clamp techniques, we found that the voltage-gated Na+ channels were tetrodotoxin sensitive and had current densities ranging from 5 to 169 pA pF−1. Analyses of the voltage dependence and kinetics revealed interesting differences from voltage-gated Na+ channels in olfactory receptor neurons from other species; the voltage of half-inactivation was shifted to the right and the voltage of half-activation was shifted to the left such that a “window-current” occurred, where 10–18% of the Na+ channels activated and did not inactivate at potentials near action potential threshold. Our findings suggest that in squid olfactory neurons, a subset of voltage-gated Na+ channels may play a role in generating a pacemaker-type current for setting the tonic levels of electrical activity required for transmission of hyperpolarizing odor responses to the brain. Accepted: 1 October 1998 |
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Keywords: | Persistent Na+ current Na+ channels Cephalopod Olfaction Patch clamp |
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