Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons

Haimann, C.; Bernheim, Laurent; Bertrand, Daniel; Bader, Charles

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Title		Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons
Authors		Haimann, C. Bernheim, Laurent Bertrand, Daniel Bader, Charles
Published in		The Journal of general physiology. 1990, vol. 95, no. 5, p. 961-979
Abstract		Whole-cell voltage clamp and single-channel recordings were performed on cultured trigeminal ganglion neurons from quail embryos in order to study a sodium-activated potassium current (KNa). When KNa was activated by a step depolarization in voltage clamp, there was a proportionality between KNa and INa at all voltages between the threshold of INa and ENa. Single-channel recordings indicated that KNa could be activated already by 12 mM intracellular sodium and was almost fully activated at 50 mM sodium. 100 mM lithium, 100 mM choline, or 5 microM calcium did not activate KNa. The relationship between the probability for the channel to be open (Po) vs. the sodium concentration and the relationship of KNa open time-distributions vs. the sodium concentration suggest that two to three sodium ions bind cooperatively before KNa channels open. KNa channels were sensitive to depolarization; at 12 mM sodium, a 42-mV depolarization caused an e-fold increase in Po. Under physiological conditions, the conductance of the KNa channel was 50 pS. This conductance increased to 174 pS when the intra- and extracellular potassium concentrations were 75 and 150 mM, respectively.
Keywords		Animals — Cells, Cultured — Membrane Potentials — Permeability — Potassium/ metabolism — Potassium Channels/ metabolism — Quail — Sodium/ metabolism — Sodium Channels/metabolism — Trigeminal Ganglion/ metabolism
Identifiers		PMID: 2163435
Full text		Article - Limited access to UNIGE Other version: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2216344/pdf/jg955961.pdf
Structures		Faculté de médecine / Section de médecine fondamentale / Département de neurosciences fondamentales
Citation (ISO format)		HAIMANN, C. et al. Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons. In: The Journal of general physiology, 1990, vol. 95, n° 5, p. 961-979. https://archive-ouverte.unige.ch/unige:10293