Rapid Characterization of hERG Channel Kinetics II: Temperature Dependence

Lei, Chon Lok; Clerx, Michael; Beattie, Kylie A.; Melgari, Dario; Hancox, Jules C.; Gavaghan, David J.; Polonchuk, Liudmila; Wang, Ken; Mirams, Gary R.

Abstract

© 2019 Biophysical Society Ion channel behavior can depend strongly on temperature, with faster kinetics at physiological temperatures leading to considerable changes in currents relative to room temperature. These temperature-dependent changes in voltage-dependent ion channel kinetics (rates of opening, closing, inactivating, and recovery) are commonly represented with Q10 coefficients or an Eyring relationship. In this article, we assess the validity of these representations by characterizing channel kinetics at multiple temperatures. We focus on the human Ether-à-go-go-Related Gene (hERG) channel, which is important in drug safety assessment and commonly screened at room temperature so that results require extrapolation to physiological temperature. In Part I of this study, we established a reliable method for high-throughput characterization of hERG1a (Kv11.1) kinetics, using a 15-second information-rich optimized protocol. In this Part II, we use this protocol to study the temperature dependence of hERG kinetics using Chinese hamster ovary cells overexpressing hERG1a on the Nanion SyncroPatch 384PE, a 384-well automated patch-clamp platform, with temperature control. We characterize the temperature dependence of hERG gating by fitting the parameters of a mathematical model of hERG kinetics to data obtained at five distinct temperatures between 25 and 37°C and validate the models using different protocols. Our models reveal that activation is far more temperature sensitive than inactivation, and we observe that the temperature dependency of the kinetic parameters is not represented well by Q10 coefficients; it broadly follows a generalized, but not the standardly-used, Eyring relationship. We also demonstrate that experimental estimations of Q10 coefficients are protocol dependent. Our results show that a direct fit using our 15-s protocol best represents hERG kinetics at any given temperature and suggests that using the Generalized Eyring theory is preferable if no experimental data are available to derive model parameters at a given temperature.

Citation

Lei, C. L., Clerx, M., Beattie, K. A., Melgari, D., Hancox, J. C., Gavaghan, D. J., Polonchuk, L., Wang, K., & Mirams, G. R. (2019). Rapid Characterization of hERG Channel Kinetics II: Temperature Dependence. Biophysical Journal, 117(12), 2455-2470. https://doi.org/10.1016/j.bpj.2019.07.030

• Journal Article Type: Article
• Acceptance Date: Jul 17, 2019
• Online Publication Date: Jul 25, 2019
• Publication Date: Dec 17, 2019
• Deposit Date: Jan 14, 2020
• Publicly Available Date: Jan 14, 2020
• Journal: Biophysical Journal
• Print ISSN: 0006-3495
• Electronic ISSN: 1542-0086
• Publisher: Biophysical Society
• Peer Reviewed: Peer Reviewed
• Volume: 117
• Issue: 12
• Pages: 2455-2470
• DOI: https://doi.org/10.1016/j.bpj.2019.07.030
• Keywords: Biophysics
• Public URL: https://nottingham-repository.worktribe.com/output/3217258
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0006349519305983
• Additional Information: This article is maintained by: Elsevier; Article Title: Rapid Characterization of hERG Channel Kinetics II: Temperature Dependence; Journal Title: Biophysical Journal; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.bpj.2019.07.030; Content Type: article; Copyright: © 2019 Biophysical Society.