Biophysical characterisation of the persistent sodium current of the Nav1.6 neuronal sodium channel: a single-channel analysis

2010 ◽  
Vol 460 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Aurélien Chatelier ◽  
Juan Zhao ◽  
Patrick Bois ◽  
Mohamed Chahine
Keyword(s):  
Sodium Channel ◽  
Single Channel ◽  
Sodium Current ◽  
Persistent Sodium Current ◽  
Single Channel Analysis ◽  
Channel Analysis

scholarly journals Single-channel Properties of Human NaV1.1 and Mechanism of Channel Dysfunction in SCN1A-associated Epilepsy

2005 ◽  
Vol 127 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Carlos G. Vanoye ◽  
Christoph Lossin ◽  
Thomas H. Rhodes ◽  
Alfred L. George
Keyword(s):  
Sodium Channel ◽  
Single Channel ◽  
Sodium Current ◽  
Febrile Seizures ◽  
Persistent Sodium Current ◽  
Open Probability ◽  
Α Subunit ◽  
Whole Cell ◽  
Open Time ◽  
Channel Properties

Mutations in genes encoding neuronal voltage-gated sodium channel subunits have been linked to inherited forms of epilepsy. The majority of mutations (>100) associated with generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI) occur in SCN1A encoding the NaV1.1 neuronal sodium channel α-subunit. Previous studies demonstrated functional heterogeneity among mutant SCN1A channels, revealing a complex relationship between clinical and biophysical phenotypes. To further understand the mechanisms responsible for mutant SCN1A behavior, we performed a comprehensive analysis of the single-channel properties of heterologously expressed recombinant WT-SCN1A channels. Based on these data, we then determined the mechanisms for dysfunction of two GEFS+-associated mutations (R1648H, R1657C) both affecting the S4 segment of domain 4. WT-SCN1A has a slope conductance (17 pS) similar to channels found in native mammalian neurons. The mean open time is ∼0.3 ms in the −30 to −10 mV range. The R1648H mutant, previously shown to display persistent sodium current in whole-cell recordings, exhibited similar slope conductance but had an increased probability of late reopening and a subfraction of channels with prolonged open times. We did not observe bursting behavior and found no evidence for a gating mode shift to explain the increased persistent current caused by R1648H. Cells expressing R1657C exhibited conductance, open probability, mean open time, and latency to first opening similar to WT channels but reduced whole-cell current density, suggesting decreased number of functional channels at the plasma membrane. In summary, our findings define single-channel properties for WT-SCN1A, detail the functional phenotypes for two human epilepsy-associated sodium channel mutants, and clarify the mechanism for increased persistent sodium current induced by the R1648H allele.

Single-channel analysis of a large conductance channel in peroxisomes from rat liver

1989 ◽  
Vol 984 (3) ◽  
pp. 351-359 ◽  
Author(s):  
Marc Lemmens ◽  
Kristine Verheyden ◽  
Paul Van Veldhoven ◽  
Johan Vereecke ◽  
Guy P. Mannaerts ◽  
...  
Keyword(s):  
Rat Liver ◽  
Single Channel ◽  
Single Channel Analysis ◽  
Large Conductance Channel ◽  
Channel Analysis
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