Persistent tetrodotoxin-resistant Na+ currents are activated by prostaglandin E2 via cyclic AMP-dependent pathway in C-type nodose neurons of adult rats

Biochem Biophys Res Commun. 2007 Apr 20;355(4):1064-8. doi: 10.1016/j.bbrc.2007.02.086. Epub 2007 Feb 26.

Abstract

It has been documented that nodose neurons express TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Na(+) channels. However, wheteher nodose neurons functionally express persistent TTX-R Na(+) currents has not been reported. The present study first demonstrated persistent TTX-R Na(+) channel activities in 7/19 C-type nodose neurons in the presence of PGE(2) using whole-cell patch. Voltage-dependent property showed that persistent TTX-R Na(+) currents were activated at near -60mV and channels were maintained open. The average peak was approximately 300-500pA. The mid-point of activation exhibited a greater shift to a more hyperpolarized potential in the neurons co-expressing TTX-R and persistent TTX-R Na(+) currents than those expressing TTX-R only. This effect of PGE(2) was also mimicked by Forskolin. The fact that persistent TTX-R Na(+) currents were only activated by PGE(2) suggested that the modulatory effects of PGE(2) on persistent TTX-R Na(+) currents are crucial in PGE(2)-mediated neuronal excitability, and may have a great impact on specifically physiological significance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aging / physiology
  • Animals
  • Cells, Cultured
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism*
  • Dinoprostone / pharmacology*
  • Electrophysiology
  • Ion Channel Gating
  • Male
  • Neurons / drug effects*
  • Neurons / metabolism*
  • Nodose Ganglion / drug effects
  • Nodose Ganglion / metabolism*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Sodium / metabolism*
  • Tetrodotoxin / pharmacology*
  • Up-Regulation

Substances

  • Colforsin
  • Tetrodotoxin
  • Sodium
  • Cyclic AMP
  • Dinoprostone