Voltage-gated tetrodotoxin-resistant sodium channel (TTX-R VGSC)

Voltage-gated tetrodotoxin-resistant (TTX-R) sodium channels are a specialized subset of the voltage-gated sodium channel family that remain functional in the presence of the potent neurotoxin tetrodotoxin. This group primarily includes the isoforms Nav1.5, Nav1.8, and Nav1.9, which are encoded by the genes SCN5A, SCN10A, and SCN11A, respectively (Catterall, 2000). While Nav1.5 is the principal sodium channel in the heart responsible for the rapid upstroke of the cardiac action potential, Nav1.8 and Nav1.9 are predominantly expressed in peripheral sensory neurons, particularly nociceptors (Bennett et al., 2019). These channels play a critical role in the initiation and propagation of pain signals, making them high-priority targets for the development of non-opioid analgesics (Eijkelkamp et al., 2012). Mutations in these channels are linked to various disorders, including cardiac arrhythmias (Nav1.5) and chronic pain syndromes like small fiber neuropathy or erythromelalgia (Nav1.8/1.9) (Dib-Hajj et al., 2013). Therapeutic strategies focus on developing selective inhibitors, such as Suzetrigine (VX-548), to block pain transmission without affecting cardiac function or central nervous system activity (Jones et al., 2023).

Other names

TTX-resistant sodium channelsTTX-insensitive sodium channelsNav1.5/Nav1.8/Nav1.9Tetrodotoxin-resistant voltage-gated sodium channels

Selective inhibition of the alpha-subunit pore to block sodium ion conductance or stabilization of the inactivated state to prevent repetitive firing.