Persistent tetrodotoxin-resistant Na+ currents are activated by prostaglandin E2 via cyclic AMP-dependent pathway in C-type nodose neurons of adult rats.
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.
Li
Baiyan
B
Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA. baili@iupui.edu
Schild
John H
JH
D000375:Aging / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology*; D004594:Electrophysiology; D015640:Ion Channel Gating; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009620:Nodose Ganglion / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology*; D015854:Up-Regulation
D005576:Colforsin; D013779:Tetrodotoxin; D012964:Sodium; D000242:Cyclic AMP; D015232:Dinoprostone