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 PGE2 using whole-cell patch. Voltage-dependent property showed that persistent TTX-R Na+ currents were activated at near −60 mV and channels were maintained open. The average peak was approximately 300-500 pA. 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 PGE2 was also mimicked by Forskolin. The fact that persistent TTX-R Na+ currents were only activated by PGE2 suggested that the modulatory effects of PGE2 on persistent TTX-R Na+ currents are crucial in PGE2-mediated neuronal excitability, and may have a great impact on specifically physiological significance.