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channels contribute to the delayed rectifier current in small cultured mouse dorsal root ganglion neurons
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| fBocksteins E, Van de Vijver G, Van Bogaert PP, Snyders DJ. K(V)3 channels contribute to the delayed rectifier current in small cultured mouse dorsal root ganglion neurons. Am J Physiol Cell Physiol 303: C406-C415, 2012. First published June 6, 2012; doi:10.1152/ajpcell.00343.2011.-Delayed rectifier voltage-gated K+ (K-V) channels are important determinants of neuronal excitability. However, the large number of K-V subunits poses a major challenge to establish the molecular composition of the native neuronal K+ currents. A large part (similar to 60%) of the delayed rectifier current (I-K) in small mouse dorsal root ganglion (DRG) neurons has been shown to be carried by both homotetrameric K(V)2.1 and heterotetrameric channels of K(V)2 subunits with silent K-V subunits (KVS), while a contribution of K(V)1 channels has also been demonstrated. Because K(V)3 subunits also generate delayed rectifier currents, we investigated the contribution of K(V)3 subunits to I-K in small mouse DRG neurons. After stromatoxin (ScTx) pretreatment to block the K(V)2-containing component, application of 1 mM TEA caused significant additional block, indicating that the ScTx-insensitive part of I-K could include K(V)1, K(V)3, and/or M-current channels (KCNQ2/3). Combining ScTx and dendrotoxin confirmed a relevant contribution of K(V)2 and K(V)2/KVS, and K(V)1 subunits to I-K in small mouse DRG neurons. After application of these toxins, a significant TEA-sensitive current (similar to 19% of total I-K) remained with biophysical properties that corresponded to those of K(V)3 currents obtained in expression systems. Using RT-PCR, we detected K(V)3.1-3 mRNA in DRG neurons. Furthermore, Western blot and immunocytochemistry using K(V)3.1-specific antibodies confirmed the presence of K(V)3.1 in cultured DRG neurons. These biophysical, pharmacological, and molecular results demonstrate a relevant contribution (similar to 19%) of K(V)3-containing channels to I-K in small mouse DRG neurons, supporting a substantial role for K(V)3 subunits in these neurons. | | |
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English
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American journal of physiology: cell physiology. - Bethesda, Md | |
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Bethesda, Md : 2012
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0363-6143
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303:4(2012), p. C406-C415
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000307804800007
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