TY - JOUR
T1 - Resurgent-like currents in mouse vas deferens myocytes are mediated by NaV1.6 voltage-gated sodium channels
AU - Teramoto, Noriyoshi
AU - Zhu, Hai Lei
AU - Yotsu-Yamashita, Mari
AU - Inai, Tetsuichiro
AU - Cunnane, Thomas C.
PY - 2012/11
Y1 - 2012/11
N2 - Patch-clamp experiments were performed to investigate the molecular properties of resurgent-like currents in single smooth muscle cells dispersed from mouse vas deferens, utilizing both NaV1.6-null mice (Na V1.6-/-), lacking the expression of the Scn8a Na + channel gene, and their wild-type littermates (Na V1.6+/+). NaV1.6 immunoreactivity was clearly visible in dispersed smooth muscle cells obtained from NaV1.6+/+, but not NaV1.6+/+, vas deferens. Following a depolarization to +30 mV from a holding potential of +70 mV (to produce maximal inactivation of the Na+ current), repolarization to voltages between -60 and +20 mV elicited a tetrodotoxin (TTX)- sensitive inward current in NaV1.6+/+, but not NaV1.6-/-, vas deferens myocytes. The resurgent-like current in NaV1.6+/+ vas deferens myocytes peaked at approximately +20 mV in the current-voltage relationship. The peak amplitude of the resurgent-like current remained at a constant level when the membrane potential was repolarized to +20 mV following the application of depolarizing rectangular pulses to more positive potentials than -20 mV. 4,9-Anhydrotetrodotoxin (4,9-anhydroTTX), a selective NaV1.6 blocking toxin, purified from a crude mixture of TTX analogues by LCFLD techniques, reversibly suppressed the resurgent-like currents. β-Pompilidotoxin, a voltage-gated Na+ channel activator, evoked sustained resurgent-like currents in Na V1.6+/+ but not NaV1.6-/- murine vas deferens myocytes. These results strongly indicate that, primarily, resurgent-like currents are generated as a result of NaV1.6 channel activity.
AB - Patch-clamp experiments were performed to investigate the molecular properties of resurgent-like currents in single smooth muscle cells dispersed from mouse vas deferens, utilizing both NaV1.6-null mice (Na V1.6-/-), lacking the expression of the Scn8a Na + channel gene, and their wild-type littermates (Na V1.6+/+). NaV1.6 immunoreactivity was clearly visible in dispersed smooth muscle cells obtained from NaV1.6+/+, but not NaV1.6+/+, vas deferens. Following a depolarization to +30 mV from a holding potential of +70 mV (to produce maximal inactivation of the Na+ current), repolarization to voltages between -60 and +20 mV elicited a tetrodotoxin (TTX)- sensitive inward current in NaV1.6+/+, but not NaV1.6-/-, vas deferens myocytes. The resurgent-like current in NaV1.6+/+ vas deferens myocytes peaked at approximately +20 mV in the current-voltage relationship. The peak amplitude of the resurgent-like current remained at a constant level when the membrane potential was repolarized to +20 mV following the application of depolarizing rectangular pulses to more positive potentials than -20 mV. 4,9-Anhydrotetrodotoxin (4,9-anhydroTTX), a selective NaV1.6 blocking toxin, purified from a crude mixture of TTX analogues by LCFLD techniques, reversibly suppressed the resurgent-like currents. β-Pompilidotoxin, a voltage-gated Na+ channel activator, evoked sustained resurgent-like currents in Na V1.6+/+ but not NaV1.6-/- murine vas deferens myocytes. These results strongly indicate that, primarily, resurgent-like currents are generated as a result of NaV1.6 channel activity.
KW - Na1.6
KW - Na channels
KW - Resurgent-like currents
KW - Scn8a
KW - Smooth muscle
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U2 - 10.1007/s00424-012-1153-4
DO - 10.1007/s00424-012-1153-4
M3 - Article
C2 - 22986623
AN - SCOPUS:84867888986
SN - 0031-6768
VL - 464
SP - 493
EP - 502
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
IS - 5
ER -