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Updated: Aug 9, 2026

Functional Site-Directed Fluorometry in Native Cells to Study Skeletal Muscle Excitability
Published on: June 2, 2023
Characterization of voltage-gated sodium-channel blockers by electrical stimulation and fluorescence detection of
Chien-Jung Huang1, Alec Harootunian, Michael P Maher
1Vertex Pharmaceuticals Incorporated, 11010 Torreyana Road, San Diego, California 92121, USA.
Abstract:
Voltage-gated ion channels regulate many physiological functions and are targets for a number of drugs. Patch-clamp electrophysiology is the standard method for measuring channel activity because it fulfils the requirements for voltage control, repetitive stimulation and high temporal resolution, but it is laborious and costly. Here we report an electro-optical technology and automated instrument, called the electrical stimulation voltage ion probe reader (E-VIPR), that measures the activity of voltage-gated ion channels using extracellular electrical field stimulation and voltage-sensitive fluorescent probes. We demonstrate that E-VIPR can sensitively detect drug potency and mechanism of block on the neuronal human type III voltage-gated sodium channel expressed in human embryonic kidney cells. Results are compared with voltage-clamp and show that E-VIPR provides sensitive and information-rich compound blocking activity. Furthermore, we screened approximately 400 drugs and observed sodium channel-blocking activity for approximately 25% of them, including the antidepressants sertraline (Zoloft) and paroxetine (Paxil).
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