title: Effects of free fatty acids on sodium currents in rat dorsal root ganglion neurons.
abstract: Free fatty acids (FFAs), especially polyunsaturated fatty acids (PUFAs), are potent modulators of muscle-type sodium channels. It is not known if they also modulate sodium channels of sensory neurons. In this study, we investigated the effects of FFAs on the fast tetrodotoxin-sensitive (fTTX-S) and the slow tetrodotoxin-resistant (sTTX-R) sodium currents in rat dorsal root ganglion neurons. At a holding potential of -80 mV, PUFAs potently inhibited fTTX-S current, but monounsaturated fatty acids (MUFAs) and saturated fatty acids (SFAs) to a lesser extent. All FFAs initially increased sTTX-R current, and then decreased it slightly. PUFAs and MUFAs produced a hyperpolarizing shift of the steady-state inactivation voltage for both types of sodium currents. The shift generally increased with the number of unsaturated bonds. FFAs did not change the maximum amplitude of fTTX-S current, but increased that of sTTX-R current. Most FFAs shifted the activation voltage for fTTX-S current in the hyperpolarizing direction, which was not dependent on the degree of unsaturation. MUFAs and SFAs shifted the activation voltage for sTTX-R current in the hyperpolarizing direction, but PUFAs were without effect. The modulation of sodium currents by FFAs, especially PUFAs, may have considerable impact on the excitability of sensory neurons.
authors.affiliation: Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuk-Suk Dong, Dong-Jak Ku, Seoul 156-756, South Korea.
authors.forename: Min-Pyo
authors.initials: MP
authors.lastname: Hong
authors.forename: Hong Im
authors.initials: HI
authors.lastname: Kim
authors.forename: Yong Kyoo
authors.initials: YK
authors.lastname: Shin
authors.forename: Chung Soo
authors.initials: CS
authors.lastname: Lee
authors.forename: Mijung
authors.initials: M
authors.lastname: Park
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Song
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D005227:Fatty Acids / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000166:cytology*; D015640:Ion Channel Gating / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D005227:Fatty Acids; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013779:Tetrodotoxin; D012964:Sodium