Radix paeoniae rubra suppression of sodium current in acutely dissociated rat hippocampal CA1 neurons.
The effect of Radix paeoniae rubra (RPR) on voltage-gated sodium channel (VGSC) currents (I(Na)) was examined in freshly isolated rat hippocampal CA1 neurons using whole-cell patch-clamp technique under voltage-clamp conditions. RPR suppressed I(Na) without affecting the current activation, inactivation and deactivation. The amplitude of I(Na) decreased by approximately 18.4% within a few seconds of 0.8 mg/ml RPR exposure. RPR (0.8 mg/ml) shifted the steady-state inactivation curves of I(Na) to negative potentials, with hyperpolarizing direction shift of V(1/2) of 10.0 mV. The time course of I(Na) recovery from inactivation was prolonged significantly by 0.8 mg/ml RPR. RPR (0.8 mg/ml) also enhanced the activity-dependent attenuation of I(Na) and decreased the fraction of activated channels. These results suggested that RPR suppressed hippocampal CA1 I(Na) by shifting the inactivation curve in hyperpolarizing direction, slowing the recovery time course from inactivation, enhancing the activity-dependent attenuation and decreasing the number of activatable channels. RPR suppression on I(Na) might predict the protective effect during brain ischemia in hippocampal CA1 neurons.
Dong
Xian-Ping
XP
Laboratory of Receptor Pharmacology, Department of Neurobiology and Biophysics, School of Life Sciences, University of Science and Technology of China, P.O. Box 4, 230027, Hefei, PR China.
Xu
Tian-Le
TL
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D029596:Paeonia; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects* / Q000378:metabolism*
D004365:Drugs, Chinese Herbal; D018696:Neuroprotective Agents; D015222:Sodium Channels; D012964:Sodium