A novel persistent tetrodotoxin-resistant sodium current in SNS-null and wild-type small primary sensory neurons
A novel persistent tetrodotoxin-resistant sodium current in SNS-null and wild-type small primary sensory neurons
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DOI：
10.1523/jneurosci.19-24-j0001.1999
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发表时间：
1999-12-15
影响因子：
5.3
通讯作者：
Waxman, SG
中科院分区：
文献类型：
--
作者：
Cummins, TR;Dib-Hajj, SD;Waxman, SG
TTX-resistant (TTX-R) sodium currents are preferentially expressed in small C-type dorsal root ganglion (DRG) neurons, which include nociceptive neurons. Two mRNAs that are predicted to encode TTX-R sodium channels, SNS and NaN, are preferentially expressed in C-type DRG cells. To determine whether there are multiple TTX-R currents in these cells, we used patch-clamp recordings to study sodium currents in SNS-null mice and found a novel persistent voltage-dependent sodium current in small DRG neurons of both SNS-null and wild-type mice. Like SNS currents, this current is highly resistant to TTX (K(i) = 39 +/- 9 mu M). In contrast to SNS currents, the threshold for activation of this current is near -70 mV, the midpoint of steady-state inactivation is -44 +/- 1 mV, and the time constant for inactivation is 43 +/- 4 msec at -20 mV. The presence of this current in SNS-null and wild-type mice demonstrates that a distinct sodium channel isoform, which we suggest to be NaN, underlies this persistent TTX-R current. Importantly, the hyperpolarized voltage-dependence of this current, the substantial overlap of its activation and steady-state inactivation curves and its persistent nature suggest that this current is active near resting potential, where it may play an important role in regulating excitability of primary sensory neurons.
