Development and Testing of an In-vitro Assay for Screening of Potential Therapeutic Agents Active against Na Channel Neurotoxins

摘要

A rapid screening assay based upon the ability of (3H)BTX-B binding to rat brain synaptoneurosomes to report sensitively on ligand-receptor interactions at any of at least five distinct sodium channel binding domains in a single assay has been refined and reduced to practice. Data are presented to demonstrate the expected response from a series of sodium channel-active agents, including tetrodotoxin (TTX), saxitoxin, alpha-scorpion toxin, local anesthetics, and pyrethroid insecticides. Further radioligand binding assays and electrophysiological testing of HM-197, a simple hexahydropyrimidine analog of TTX, shows that its relatively potent effect to inhibit the binding of (3H)BTX-B is not mediated through an interaction at sodium channel binding sites for TTX, local anesthetics or batrachotoxin.