Voltage-gated sodium channel (VGSC) local anesthetic receptor site (VGSC-LA site)

Voltage-gated sodium channels (VGSCs) are transmembrane proteins that play a critical role in the generation and propagation of action potentials in excitable cells, including neurons and myocytes (StatPearls [https://www.ncbi.nlm.nih.gov/books/NBK532905/]). The local anesthetic (LA) binding site is a pharmacologically vital region located within the internal pore of the channel's alpha subunit, specifically involving the S6 transmembrane segments (Catterall, J Physiol, 2012 [https://pubmed.ncbi.nlm.nih.gov/22451618/]). When local anesthetics or certain antiarrhythmic drugs bind to this site, they physically obstruct the pore and stabilize the channel in its non-conducting inactivated state (Nau and Wang, J Membr Biol, 2004 [https://pubmed.ncbi.nlm.nih.gov/15455144/]). This action prevents the influx of sodium ions, thereby inhibiting the depolarization necessary for nerve impulse transmission and muscle contraction (Tikhonov and Zhorov, Mar Drugs, 2012 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3354418/]). Clinically, this site is the primary target for drugs used to induce regional anesthesia, manage chronic and acute pain, and control cardiac arrhythmias or epileptic seizures (Bagal et al., Channels, 2015 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4826128/]). However, systemic absorption of drugs targeting this site can lead to serious safety concerns, such as local anesthetic systemic toxicity (LAST), which manifests as central nervous system excitation followed by depression and potentially fatal cardiovascular collapse (StatPearls [https://www.ncbi.nlm.nih.gov/books/NBK532905/]). Understanding the structural biology of this site has been essential for developing more selective sodium channel blockers with improved safety profiles (Bagal et al., Channels, 2015 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4826128/]).

Other names

Local anesthetic binding siteIntracellular pore binding siteLA binding siteSodium channel pore receptor site

Use-dependent blockade of the internal pore of the sodium channel alpha subunit, physically obstructing sodium ion conductance and stabilizing the inactivated state of the channel (StatPearls [https://www.ncbi.nlm.nih.gov/books/NBK532905/]).