Kinetic properties of tetrodotoxin-sensitive and tetrodotoxin-resistant sodium channel currents in neonatal rat trigeminal ganglion neurons.
The kinetic properties of tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na' channels in acutely dissociated neonatal rat trigeminal ganglion neurons were studied using whole-cell and cell-attached patch-clamp recordings. The time course of TTX-R currents was slower than that of TTX-S currents. Compared with TTX-S currents, TTX-R currents had more positive half-activation and half-inactivation voltages. TTX-R currents recovered from inactivation much faster than TTX-S currents. Cell-attached patch recordings showed that the slope conductance of single TTX-S and TTX-R channels was 14.6 pS and 7.8 pS, respectively. TTX-R channels had longer open-times and more dispersed latent-times than TTX-S channels. The convolution of the first latency distribution with the open-time distribution revealed that the slower time course of TTX-R currents is due to longer open-times and more dispersed latent-times of the TTX-R channels compared with those of the TTX-S channels. These findings suggest that TTX-R Na+ channels in trigeminal ganglion neurons have similar kinetic property to brain TTX-S Na+ channels, but not to structurally homologous cardiac Na+ channels.
Gotoh
Masamichi
M
Department of Restorative Sciences, Tokyo Medical and Dental University, Japan. m_gotoh@yahoo.co.jp
Noro
Nobuhiro
N
Sahara
Yoshinori
Y
D000200:Action Potentials / Q000187:drug effects; D000465:Algorithms; D000818:Animals; D000831:Animals, Newborn; D004587:Electrophoresis, Agar Gel; D005071:Evoked Potentials / Q000187:drug effects; D015640:Ion Channel Gating / Q000187:drug effects; D017136:Ion Transport / Q000187:drug effects; D007700:Kinetics; D016018:Least-Squares Analysis; D008564:Membrane Potentials / Q000187:drug effects; D009431:Neural Conduction / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D016011:Normal Distribution; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D012815:Signal Processing, Computer-Assisted; D015222:Sodium Channels / Q000187:drug effects*; D013223:Statistics as Topic; D013779:Tetrodotoxin / Q000494:pharmacology*; D013997:Time Factors; D012668:Trigeminal Ganglion / Q000187:drug effects*
D015222:Sodium Channels; D013779:Tetrodotoxin