Channelpedia

PubMed 11781292


Referenced in: none

Automatically associated channels: Nav1.5



Title: Sodium current in human jejunal circular smooth muscle cells.

Authors: Adrian N Holm, Adam Rich, Steven M Miller, Peter Strege, Yijun Ou, SimonJ Gibbons, Michael G Sarr, Joseph H Szurszewski, James L Rae, Gianrico Farrugia

Journal, date & volume: Gastroenterology, 2002 Jan , 122, 178-87

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11781292


Abstract
Sodium channels are key regulators of neuronal and muscle excitability. However, sodium channels have not been definitively identified in gastrointestinal smooth muscle. The aim of the present study was to determine if a Na(+) current is present in human jejunal circular smooth muscle cells.Currents were recorded from freshly dissociated cells using patch-clamp techniques. Complementary DNA (cDNA) libraries constructed from the dissociated cells were screened to determine if a message for alpha subunits of Na(+) channels was expressed. Smooth muscle cells were also collected using laser-capture microdissection and screened.A tetrodotoxin-insensitive Na(+) channel was present in 80% of cells patch-clamped. Initial activation was at -65 mV with peak inward current at -30 mV. Steady-state inactivation and activation curves revealed a window current between -75 and -60 mV. The Na(+) current was blocked by lidocaine and internal and external QX314. A cDNA highly homologous to SCN5A, the alpha subunit of the cardiac Na(+) channel, was present in the cDNA libraries constructed from dissociated cells and from smooth muscle cells collected using laser-capture microdissection.Human jejunal circular smooth muscle cells express a tetrodotoxin-insensitive Na(+) channel, probably SCN5A. Whether SCN5A plays a role in the pathophysiology of human gut dysmotilities remains to be determined.