Question

Some vanillotoxins, present in the venom of some spiders such as tarantulas, inhibit voltage-gated K+channels, preventing them from opening.

Q: Will exposure to vanillotoxin make this neuron more likely or less likely to fire an action potential?

Answer 1

Exposure to vanillotoxin make the neuron more likely to fire an action potential. In normal case, the voltage gated K+ channels remain closed during resting membrane potential (RMP) as well as during depolarization. They open to cause efflux of K+ ions during repolarization and leads the neuron to RMP. When vanillotoxin is injected, K+ channels remain closed affecting repolarization. Hence, it will be easier to fire next action potential in the same neuron as it has not reached back to the RMP.