Question

Dendrotoxins, produced by the mamba snakes (Dendroaspis), are inhibitors of the voltage-gated K⁺ channels. What phase of the action potential would this toxin affect? How would it affect ion permeability during this phase? How would ion movement be affected?

Answer 1

Dendrotoxin affects the voltage gated potassium channels. These channels are important during the depolarization phase of the action potential. These channels move potassium out which makes the membrane potential negative and repolarization occurs. When these channels are blocked, potassium efflux cannot occur , hence ,repolarization doesn't occur. The K will stay inside which will make the membrane potential positive. There will be sustained action potential depolarization. Voltage gated K channels are also needed to bring the membrane potential back to the resting level. Hence, the potential is not able to come to the resting level.

Normal action potential