Brevetoxin-3 (PbTx-3) is a potent allosteric voltage-gated Na+ channel activator. Brevetoxin-3 has a high affinity to site 5 of the voltage-sensitive Na+ channels, inhibits the inactivation of Na+ channels.

Na+-ATPase:

Brevetoxin-3 (30-500 nM) produces a shift in activation to more negative membrane potentials whereby single-channel activity is observed under steady-state conditions (maintained depolarization at -50 mV) [1].

Brevetoxin-3 (intratracheal instillation; 2.8 μg/kg; gestational days 15-18) radioactivity is detected in placentas and fetuses within 0.5 hours. Concentrations of brevetoxin equivalents in fetuses are approximately 0.3 ng/g throughout the 48-h post-dosing, resulting in a calculated dose to fetuses of 19 ng/gh [3].