Phrixotoxins are peptide toxins derived from the venom of the Chilean copper tarantula Phrixotrichus auratus, also named Paraphysa scrofa.

Phrixotoxin-3 (PaurTx3) inhibits several voltage gated sodium channel subtypes (Nav1.1/SCN1A, Nav1.2/SCN2A, Nav1.4/SCN4A, Nav1.5/SCN5A, and Nav1.8/SCN10A) (Bosmans 2006) harv error: no target: CITEREFBosmans2006 (help).

Inhibition results from a shift of the conductance-voltage relation and steady-state inactivation properties to more depolarized potentials.

Phrixotoxin-3 modulates voltage-gated sodium channels by causing a depolarizing shift in gating kinetics and by blocking the inward component of sodium current, thus preventing the channels from opening to a moderate depolarization, resulting in a reduced firing rate of the neurons (Bosmans 2006) harv error: no target: CITEREFBosmans2006 (help).

These effects are seen following both intravenous and intracisternal injection, making it likely that phrixotoxin-1 crosses the blood brain barrier (Diochot 1999) harv error: no target: CITEREFDiochot1999 (help).

Injection of this venom into mice causes immediate general ataxia, lack to response stimuli and semi-paralysis.

Flaccid paralysis and slowing of breathing eventually cause death (Bosmans 2006) harv error: no target: CITEREFBosmans2006 (help).

"Solution structure of Phrixotoxin 1, a specific peptide inhibitor of Kv4 potassium channels from the venom of the theraphosid spider Phrixotrichus auratus".