Biology subjects

Waxman, S. G.

Publications and source records attributed to Waxman, S. G..

3 recordsLinked to original sources

bioRxiv2026

APpar: automated action potential parameter analysis software for reproducible electrophysiological measurements in neurons

Quantitative analysis of action potential (AP) waveforms is central to studies of neuronal excitability, ion channel function, disease mechanisms, and pharmacological modulation. However, AP analysis is still often performed using partially manual workflows, laboratory-specific spreadsheets, or proprietary software environments that can limit reproducibility, transparency, and throughput. Here we present APpar, a freely available, open-source software tool for extracting AP parameters, developed for use with the OriginLab software package Origin/OriginPro. APpar detects APs from membrane voltage recordings using a user-defined derivative criterion and calculates a comprehensive set of excitability parameters, including resting membrane potential, AP threshold, dV/dt at threshold, overshoot, undershoot, AP amplitude, AP half-amplitude, rise time, decay time, AP duration, AP half-width, AP width at 0 mV, AP area above voltage threshold, dV/dtMAX, dV/dtMIN, interspike interval for the respective AP. Because AP threshold is a particularly sensitive and method-dependent measurement, APpar includes a TRUE-threshold validation algorithm. After the initial forward dV/dt threshold crossing is identified, the software finds AP overshoot, searches backward to the closest preceding local dV/dt maximum, then searches backward to the user-defined dV/dt crossing and recalculates AP parameters from this validated threshold point. We validated APpar using APs from dorsal root ganglion neurons current-clamp recordings, including copied identical APs, current-evoked repetitive firing, and long-duration spontaneous firing. The software produced stable measurements from identical copied APs and extracted dynamic changes in AP parameters across repetitive and spontaneous firing sequences. APpar provides a transparent, customizable, and Origin-compatible framework for reproducible AP analysis in neuronal electrophysiology. Significance statementAction potential waveform analysis is essential for interpreting neuronal excitability, but many AP measurements remain vulnerable to user-dependent threshold placement, manual cursor selection, and inconsistent parameter definitions. APpar, a freely available, open-source software tool, addresses this problem by automating AP detection and parameter extraction within the OriginLab environment widely available to electrophysiology laboratories. The software formalizes definitions of AP threshold, amplitude, duration, half-width, afterhyperpolarization, derivative-based parameters, and firing metrics, and introduces a TRUE-threshold validation algorithm that recalculates AP parameters from a derivative-validated threshold point. This workflow reduces operator-dependent variability while preserving user control over physiologically meaningful detection criteria. HighlightsAutomated action potential waveform analysis within OriginLab Origin environments AP threshold validation improves reproducibility of derivative-based threshold detection Extracts action potential kinetics, amplitudes, widths, and dV/dt measurements Open-source workflow supports reproducible neuronal electrophysiology data analysis Validated using repetitive and spontaneous firing in DRG neurons

biophysics↗

bioRxiv2025

Targeted ubiquitination of NaV1.8 reduces sensory neuronal excitability

Chronic pain and addiction are a significant global health challenge. Voltage-gated sodium channel NaV1.8, a pivotal driver of pain signaling, is a clinically validated target for the development of novel, non-addictive pain therapeutics. Small molecule inhibitors against NaV1.8 have shown promise in acute pain indications, but large clinical effect sizes have not yet been demonstrated and efficacy in chronic pain indications are lacking. An alternative strategy to target NaV1.8 channels for analgesia is to reduce the number of channels that are present on nociceptor membranes. We generated a therapeutic heterobifunctional protein, named UbiquiNaV, that contains a NaV1.8-selective binding module and the catalytic subunit of the NEDD4 E3 Ubiquitin ligase. We show that UbiquiNav significantly reduces channel expression in the plasma membrane and reduces NaV1.8 currents in rodent sensory neurons. We demonstrate that UbiquiNaV is selective for NaV1.8 over other NaV isoforms and other components of the sensory neuronal electrogenisome. We then show that UbiquiNaV normalizes the distribution of NaV1.8 protein to distal axons, and that UbiquiNaV normalizes the neuronal hyperexcitability in in vitro models of inflammatory and chemotherapy-induced neuropathic pain. Our results serve as a blueprint for the design of therapeutics that leverage the selective ubiquitination of NaV1.8 channels for analgesia.

neuroscience↗

bioRxiv2021

Inhibition of sodium conductance by cannabigerol contributes to a reduction of neuronal dorsal root ganglion excitability

Cannabigerol (CBG), a non-psychotropic phytocannabinoid, is a precursor for cannabis derivatives, {Delta}9-tetrahydrocannabinol and cannabidiol (CBD). Like CBD, CBG has been suggested as an analgesic. A previous study reported CBG (10 M) blocks voltage-gated sodium (Nav) currents in CNS neurons. However, the manner in which CBG inhibits Nav channels, and whether this effect contributes to CBGs potential analgesic behavior remain unknown. Genetic and functional studies have validated Nav1.7 as an opportune target for analgesic drug development. The efforts to develop therapeutic selective Nav1.7 blockers have been unsuccessful thus far, possibly due to issues in occupancy; drugs have been administered at concentrations many folds above IC50, resulting in loss of isoform-selectivity, and increasing off-target effects. We reasoned that an alternative approach could use compounds possessing 2 important properties: ultra-hydrophobicity and functional selectivity. Hydrophobicity could enhance absorption into neuronal cells especially with local administration. Functional selectivity could reduce likelihood of side-effects. As CBG is ultra-hydrophobic (cLogD=7.04), we sought to determine whether it also possesses functional selectivity against Nav channels that are expressed in dorsal root ganglion (DRG). We found that CBG is a ~10-fold state-dependent Nav inhibitor (KI-KR: ~2-20 M) with an average Hill-slope of ~2. We determined that at lower concentrations, CBG predominantly blocks sodium Gmax and slows recovery from inactivation; however, as concentration is increased, CBG also hyperpolarizes Nav inactivation curves. Our modeling and multielectrode array recordings suggest that CBG attenuates DRG excitability, which is likely linked with Nav inhibition. As most Nav1.7 channels are inactivated at DRG resting membrane potential, they are more likely to be inhibited by lower CBG concentrations, suggesting functional selectivity against Nav1.7 compared to other Navs (via Gmax block).

pharmacology and toxicology↗