title: Hypotonicity modulates tetrodotoxin-sensitive sodium current in trigeminal ganglion neurons.
abstract: Voltage-gated sodium channels (VGSCs) play an important role in the control of membrane excitability. We previously reported that the excitability of nociceptor was increased by hypotonic stimulation. The present study tested the effect of hypotonicity on tetrodotoxin-sensitive sodium current (TTX-S current) in cultured trigeminal ganglion (TG) neurons. Our data show that after hypotonic treatment, TTX-S current was increased. In the presence of hypotonicity, voltage-dependent activation curve shifted to the hyperpolarizing direction, while the voltage-dependent inactivation curve was not affected. Transient Receptor Potential Vanilloid 4 receptor (TRPV4) activator increased TTX-S current and hypotonicity-induced increase was markedly attenuated by TRPV4 receptor blockers. We also demonstrate that inhibition of PKC attenuated hypotonicity-induced inhibition, whereas PKA system was not involved in hypotonic-response. We conclude that hypotonic stimulation enhances TTX-S current, which contributes to hypotonicity-induced nociception. TRPV4 receptor and PKC intracellular pathway are involved in the increase of TTX-S current by hypotonicity.
authors.affiliation: Department of Physiology, Nanjing Medical University, Nanjing, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Changjin
authors.initials: C
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007038:Hypotonic Solutions / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D012668:Trigeminal Ganglion / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D007038:Hypotonic Solutions; D013779:Tetrodotoxin; D012964:Sodium