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Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons

Haimann, C.
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 AnimalsCells, CulturedMembrane PotentialsPermeabilityPotassium/ metabolismPotassium Channels/ metabolismQuailSodium/ metabolismSodium Channels/metabolismTrigeminal Ganglion/ metabolism
PMID: 2163435
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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

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Deposited on : 2010-08-06

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