Referenced in: none

Automatically associated channels: Nav1.8 , Nav1.9

Title: Expression of tetrodotoxin-sensitive and resistant sodium channels by rat melanotrophs.

Authors: Yannick Schwab, Ronald Jahke, Emmanuel Jover

Journal, date & volume: Neuroreport, 2004 May 19 , 15, 1219-23

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/15129178

Abstract
Rat melanotrophs fire Na+ and Ca2(+)-dependent action potentials. Whereas the molecular identity of Ca2+ channels expressed by these cells is well documented, less is known about Na channels. We characterize the expression of seven sodium channel alpha-subunit and the beta1- and beta2-subunit mRNAs. The tetrodotoxin-resistant Nav1.8 and Nav1.9 alpha subunit mRNAs are detected in the newborn intermediate lobe and in cultured melanotrophs. Electrophysiological recordings further demonstrate the expression of both tetrodotoxin-sensitive and tetrodotoxin-resistant currents by dissociated melanotrophs. Moreover, activated sodium channels are able to elicit intracellular calcium waves, both in the absence or in the presence of tetrodotoxin. This work shows that rat melanotrophs express functional tetrodotoxin-resistant sodium channels, whose activation can lead to the generation of intracellular calcium waves.