The paracetamol metabolite N-acetyl-4-benzoquinoneimine (NAPQI) prevents modulation of KV7 channels via G-protein coupled receptors by interference with PIP2 and Ca2+ sensitivity

• Published in: British journal of pharmacology 2024-12
• Main Authors: Losgott, Thomas, Kudlacek, Oliver, Yang, Jae-Won, Schicker, Klaus W, Boehm, Stefan, Salzer, Isabella
• Format: Article
• Language: English
• ISSN: 1476-5381; 1476-5381
• DOI: 10.1111/bph.17419

Paracetamol has been found to alleviate inflammatory pain by modulating KV7 channels. Its metabolite N-acetyl-4-benzoquinoneimine (NAPQI) increases currents through these channels via a stretch of three cysteine residues in the channel S2-S3 linker. Through this effect, the excitability of neurons in the pain pathway is dampened. Inflammatory mediators, in turn, enhance the excitability of sensory neurons by inhibiting KV7 channels. Here, a specific interaction between NAPQI and the so-called inflammatory soup was investigated.BACKGROUND AND PURPOSEParacetamol has been found to alleviate inflammatory pain by modulating KV7 channels. Its metabolite N-acetyl-4-benzoquinoneimine (NAPQI) increases currents through these channels via a stretch of three cysteine residues in the channel S2-S3 linker. Through this effect, the excitability of neurons in the pain pathway is dampened. Inflammatory mediators, in turn, enhance the excitability of sensory neurons by inhibiting KV7 channels. Here, a specific interaction between NAPQI and the so-called inflammatory soup was investigated.Currents through KV7 channels were measured in sensory neurons and after heterologous expression in tsA201 cells. In addition, changes in cytosolic Ca2+ and in the distribution of PIP2 (PI(4,5)P2) between membrane and cytosol were determined by fluorescence microscopy.EXPERIMENTAL APPROACHCurrents through KV7 channels were measured in sensory neurons and after heterologous expression in tsA201 cells. In addition, changes in cytosolic Ca2+ and in the distribution of PIP2 (PI(4,5)P2) between membrane and cytosol were determined by fluorescence microscopy.NAPQI abolished Ca2+-mediated inhibitory effects of an 'inflammatory soup' containing ADP, ATP, bradykinin, histamine, 5-hydroxytryptamine, prostaglandin E2, substance P and a PAR2 agonist on KV7 channel currents in sensory neurons. Moreover, the increase of KV7.2 channel currents by quenching of cytosolic Ca2+ as well as the current decrease by depletion of membrane PIP2 was impaired by NAPQI. These effects were lost in mutant channels lacking the three cysteines in the S2-S3 linker.KEY RESULTSNAPQI abolished Ca2+-mediated inhibitory effects of an 'inflammatory soup' containing ADP, ATP, bradykinin, histamine, 5-hydroxytryptamine, prostaglandin E2, substance P and a PAR2 agonist on KV7 channel currents in sensory neurons. Moreover, the increase of KV7.2 channel currents by quenching of cytosolic Ca2+ as well as the current decrease by deple