8.B.19.2.8
ω-ctenitoxin-Pn3a of 116 aas and 1 N-terminal TMS. This toxin is a potent and practically irreversible antagonist of both Cav2.1/CACNA1A and Cav2.2/CACNA1B calcium channels, while it displays a partial and rapidly reversible block of Cav2.3/CACNA1E calcium channels and no effect on Cav3/CACNA1 calcium channels (Cassola et al. 1998). It also inhibits glutamate uptake from rat brain synaptosomes by an interaction between cysteines from both glutamate transporter and toxin (Reis et al. 1999). It blocks potassium-induced exocytosis of synaptic vesicles in brain cortical synaptosomes with an IC₅₀ of 1.1 nM. In mice, induces rapid general flaccid paralysis followed by death in 10-30 minutes at dose levels of 5 µg per mouse. In rat brain, it inhibits glutamate release, neuronal death and loss of neurotransmission in the hippocampus resulting from ischemia (Pinheiro et al. 2009).