Cold and warmth intensify pain-linked sodium channel gating effects and persistent currents

Abstract

Voltage-gated sodium channels (Nav) are key players in excitable tissues with the capability to generate and propagate action potentials. Mutations in the genes encoding Navs can lead to severe inherited diseases, and some of these so-called channelopathies show temperature-sensitive phenotypes, for example, paramyotonia congenita, Brugada syndrome, febrile seizure syndromes, and inherited pain syndromes like erythromelalgia (IEM) and paroxysmal extreme pain disorder (PEPD). Nevertheless, most investigations of mutation-induced gating effects have been conducted at room temperature, and thus the role of cooling or warming in channelopathies remains poorly understood. Here, we investigated the temperature sensitivity of four Nav subtypes: Nav1.3, Nav1.5, Nav1.6, and Nav1.7, and two mutations in Nav1.7 causing IEM (Nav1.7/L823R) and PEPD (Nav1.7/I1461T) expressed in cells of the human embryonic kidney cell line using an automated patch clamp system. Our experiments at 15°C, 25°C, and 35°C revealed a shift of the voltage dependence of activation to more hyperpolarized potentials with increasing temperature for all investigated subtypes. Nav1.3 exhibited strongly slowed inactivation kinetics compared with the other subtypes that resulted in enhanced persistent current, especially at 15°C, indicating a possible role in cold-induced hyperexcitability. Impaired fast inactivation of Nav1.7/I1461T was significantly enhanced by a cooling temperature of 15°C. The subtype-specific modulation as well as the intensified mutation-induced gating changes stress the importance to consider temperature as a regulator for channel gating and its impact on cellular excitability as well as disease phenotypes.

Sodium channels expressed in nociceptors contribute distinctly to action potential subthreshold phase, upstroke and shoulder

“…When reviewing raw data, several of these outliers appeared to result of measurement artifacts, so that it might be worthwhile to amend an outlier analysis. To compensate for outliers destabilizing statistical results, usage of high-throughput, automated patch-clamp systems could also be considered, as they offer a time-efficient method to gather large data sets (Kriegeskorte et al 2023, Thompson et al 2023).…”

“…Larger studies which compare VGSC gating in the same experimental setting were focusing either on CNS VGSCs and their mutations leading e.g. to epilepsy (Thompson et al 2023), or on sensory neuron sodium channels and their temperature dependence (Kriegeskorte et al 2023).…”

Dendritic excitations govern back-propagation via a spike-rate accelerometer

“…This temperature effect could explain the difference between our results and prior measurements at room temperature of bAP propagation into distal dendrites. 7 Simulations that account for the different temperature sensitivities of A-type KV channels and NaV channels 60,61 predicted temperature-sensitive back-propagation dynamics. 39 Electrophysiology Somatic whole-cell recordings were acquired from hippocampal CA1 pyramidal neurons using a custom upright microscope.…”

Development of automated patch clamp assays to overcome the burden of variants of uncertain significance in inheritable arrhythmia syndromes

“…At an experimental level, temperature control can also be an issue, which is important to study ion channel kinetics of temperature-sensitive variants ( Vandenberg et al, 2006 ; Abdelsayed et al, 2015 ; Lei et al, 2019 ; Jones, 2022 ; Ren et al, 2022 ; Kriegeskorte et al, 2023 ). Whilst temperature can be preset on most APC systems (e.g., Biolin Scientific, Fluxion and Nanion Technologies, Table 1 ), most APC assays for cardiac ion channels have been conducted at room temperature ( Vanoye et al, 2018 ; Glazer et al, 2020b ; Ng et al, 2021 ) due to an inherent instability of cell membranes at physiological temperatures leading to lower success rates.…”