Open AccessSlack and Slick K Na channels are required for the depolarizing afterpotential of acutely isolated, medium diameter rat dorsal root ganglion neurons 1
Author(s) -
GAO Shangbang,
WU Ying,
LÜ Caixia,
GUO Zhaohua,
LI Chenhong,
DING Jiuping
Publication year - 2008
Publication title -
acta pharmacologica sinica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.514
H-Index - 90
eISSN - 1745-7254
pISSN - 1671-4083
DOI - 10.1111/j.1745-7254.2008.00842.x
Subject(s) - dorsal root ganglion , depolarization , biophysics , repolarization , patch clamp , tetrodotoxin , chemistry , electrophysiology , membrane potential , neuron , anatomy , neuroscience , dorsum , biology
Aim: Na + ‐activated K + (K Na ) channels set and stabilize resting membrane potential in rat small dorsal root ganglion (DRG) neurons. However, whether K Na channels play the same role in other size DRG neurons is still elusive. The aim of this study is to identify the existence and potential physiological functions of K Na channels in medium diameter (25–35 μm) DRG neurons. Methods: Inside‐out and whole‐cell patch‐clamp were used to study the electrophysiological characterizations of native K Na channels. RT‐PCR was used to identify the existence of Slack and Slick genes. Results: We report that K Na channels are required for depolarizing afterpotential (DAP) in medium sized rat DRG neurons. In inside‐out patches, K Na channels represented 201 pS unitary chord conductance and were activated by cytoplasmic Na + [the half maximal effective concentration (EC 50 ): 35 mmol/L] in 160 mmol/L symmetrical K + o /K + i solution. Additionally, these K Na channels also represented cytoplasmic Cl − ‐dependent activation. RT‐PCR confirmed the existence of Slack and Slick genes in DRG neurons. Tetrodotoxin (TTX, 100 nmol/L) completely blocked the DRG inward Na + currents, and the following outward currents which were thought to be K Na currents. The DAP was increased when extracellular Na + was replaced by Li + . Conclusion: We conclude that Slack and Slick K Na channels are required for DAP of medium diameter rat DRG neurons that regulate DRG action potential repolarization.