title: Molecular and biophysical properties of voltage-gated Na+ channels in murine vas deferens.
abstract: The biological and molecular properties of tetrodotoxin (TTX)-sensitive voltage-gated Na(+) currents (I(Na)) in murine vas deferens myocytes were investigated using patch-clamp techniques and molecular biological analyses. In whole-cell configuration, a fast, transient inward current was evoked in the presence of Cd(2+), and was abolished by TTX (K(d) = 11.2 nM), mibefradil (K(d) = 3.3 microM), and external replacement of Na(+) with monovalent cations (TEA(+), Tris(+), and NMDG(+)). The fast transient inward current was enhanced by veratridine, an activator of voltage-gated Na(+) channels, suggesting that the fast transient inward current was a TTX-sensitive I(Na). The values for half-maximal (V(half)) inactivation and activation of I(Na) were -46.3 mV and -26.0 mV, respectively. RT-PCR analysis revealed the expression of Scn1a, 2a, and 8a transcripts. The Scn8a transcript and the alpha-subunit protein of Na(V)1.6 were detected in smooth muscle layers. Using Na(V)1.6-null mice (Na(V)1.6(-/-)) lacking the expression of the Na(+) channel gene, Scn8a, I(Na) were not detected in dispersed smooth muscle cells from the vas deferens, while TTX-sensitive I(Na) were recorded in their wild-type (Na(V)1.6(+/+)) littermates. This study demonstrates that the molecular identity of the voltage-gated Na(+) channels responsible for the TTX-sensitive I(Na) in murine vas deferens myocytes is primarily Na(V)1.6.
authors.affiliation: Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hai-Lei
authors.initials: HL
authors.lastname: Zhu
authors.forename: Manami
authors.initials: M
authors.lastname: Aishima
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Morinaga
authors.forename: Richard D
authors.initials: RD
authors.lastname: Wassall
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shibata
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Iwasa
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nomura
authors.forename: Masaya
authors.initials: M
authors.lastname: Nagao
authors.forename: Katsuo
authors.initials: K
authors.lastname: Sueishi
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Cunnane
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Teramoto
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D015640:Ion Channel Gating / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000502:physiology*; D014649:Vas Deferens / Q000502:physiology*
chemical_list: D015222:Sodium Channels; D012964:Sodium