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Expression and function of the Scn5a-encoded voltage-gated sodium channel NaV 1.5 in the rat jejunum. Neurogastroenterol Motil 2016 Jan;28(1):64-73

Date

10/16/2015

Pubmed ID

26459913

Pubmed Central ID

PMC4688076

DOI

10.1111/nmo.12697

Scopus ID

2-s2.0-84952637081   8 Citations

Abstract

BACKGROUND: The SCN5A-encoded voltage-gated sodium channel NaV 1.5 is expressed in human jejunum and colon. Mutations in NaV 1.5 are associated with gastrointestinal motility disorders. The rat gastrointestinal tract expresses voltage-gated sodium channels, but their molecular identity and role in rat gastrointestinal electrophysiology are unknown.

METHODS: The presence and distribution of Scn5a-encoded NaV 1.5 was examined by PCR, Western blotting and immunohistochemistry in rat jejunum. Freshly dissociated smooth muscle cells were examined by whole cell electrophysiology. Zinc finger nuclease was used to target Scn5a in rats. Lentiviral-mediated transduction with shRNA was used to target Scn5a in rat jejunum smooth muscle organotypic cultures. Organotypic cultures were examined by sharp electrode electrophysiology and RT-PCR.

KEY RESULTS: We found NaV 1.5 in rat jejunum and colon smooth muscle by Western blot. Immunohistochemistry using two other antibodies of different portions of NaV 1.5 revealed the presence of the ion channel in rat jejunum. Whole cell voltage-clamp in dissociated smooth muscle cells from rat jejunum showed fast activating and inactivating voltage-dependent inward current that was eliminated by Na(+) replacement by NMDG(+) . Constitutive rat Scn5a knockout resulted in death in utero. NaV 1.5 shRNA delivered by lentivirus into rat jejunum smooth muscle organotypic culture resulted in 57% loss of Scn5a mRNA and several significant changes in slow waves, namely 40% decrease in peak amplitude, 30% decrease in half-width, and 7 mV hyperpolarization of the membrane potential at peak amplitude.

CONCLUSIONS & INFERENCES: Scn5a-encoded NaV 1.5 is expressed in rat gastrointestinal smooth muscle and it contributes to smooth muscle electrophysiology.

Author List

Beyder A, Gibbons SJ, Mazzone A, Strege PR, Saravanaperumal SA, Sha L, Higgins S, Eisenman ST, Bernard CE, Geurts A, Kline CF, Mohler PJ, Farrugia G

Author

Aron Geurts PhD Professor in the Physiology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Blotting, Western
Colon
Immunohistochemistry
Jejunum
Membrane Potentials
Myocytes, Smooth Muscle
NAV1.5 Voltage-Gated Sodium Channel
Patch-Clamp Techniques
RNA, Messenger
Rats
Reverse Transcriptase Polymerase Chain Reaction