Research

Temperature dependence of erythromelalgia mutation L858F in sodium channel Nav1.7

Chongyang Han^1* , Angelika Lampert^2,3,4* , Anthony M Rush^2,3,4,6 , Sulayman D Dib-Hajj^2,3,4 , Xiaoliang Wang¹ , Yong Yang⁵ and Stephen G Waxman^2,3,4

¹  Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China

²  Department of Neurology

³  Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA

⁴  Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare Center, West Haven, CT 06516, USA

⁵  Department of Dermatology, Peking University First Hospital, Beijing, China, 100034

⁶  NeuroSolutions Ltd., PO Box 3517, Coventry CV4 7ZS, UK

author email corresponding author email* Contributed equally

Molecular Pain 2007, 3:3doi:10.1186/1744-8069-3-3

Published:	19 January 2007

Abstract

Background

The disabling chronic pain syndrome erythromelalgia (also termed erythermalgia) is characterized by attacks of burning pain in the extremities induced by warmth. Pharmacological treatment is often ineffective, but the pain can be alleviated by cooling of the limbs. Inherited erythromelalgia has recently been linked to mutations in the gene SCN9A, which encodes the voltage-gated sodium channel Nav1.7. Nav1.7 is preferentially expressed in most nociceptive DRG neurons and in sympathetic ganglion neurons. It has recently been shown that several disease-causing erythromelalgia mutations alter channel-gating behavior in a manner that increases DRG neuron excitability.

Results

Here we tested the effects of temperature on gating properties of wild type Nav1.7 and mutant L858F channels. Whole-cell voltage-clamp measurements on wild type or L858F channels expressed in HEK293 cells revealed that cooling decreases current density, slows deactivation and increases ramp currents for both mutant and wild type channels. However, cooling differentially shifts the midpoint of steady-state activation in a depolarizing direction for L858F but not for wild type channels.

Conclusion

The cooling-dependent shift of the activation midpoint of L858F to more positive potentials brings the threshold of activation of the mutant channels closer to that of wild type Nav1.7 at lower temperatures, and is likely to contribute to the alleviation of painful symptoms upon cooling in affected limbs in patients with this erythromelalgia mutation.