Tetraethylammonium (TEA) is a potent neurotoxin that results in death from respiratory failure within 10 to 30 minutes. When a neuron is incubated with TEA, researchers observed that action potentials could be generated, but that the membrane potential remained positive and never returned to the resting membrane potential. Use this information to answer the following question. What channel is TEA likely acting on?

Answer: B Voltage gated potassium channels.

A) voltage-gated sodium channels

B) voltage-gated potassium channels

C) sodium potassium pumps

D) chloride channels

Explanation:

Tetraethylammonium is a pH - potassium channel blocker; which prevents escape of potassium ions from the intracellular layer of the axon, by blocking the channels. This increases positive ion concentration of the inner axon, (together with other positive charged molecules in the axoplasm). since potassium is a positively charged and intracellular ion

Due to the fact that (TEA) is pH - potassium ion blocker; it has no inhibitory effect on the voltage-gated sodium ion channels, so action potential can progresses. But after the sodium gated channels were closed, action potential drops but the concentration of positive charged potassium ions increases because-

They cannot leave the axoplasm since the potassium votage gated channels has been shu by (TEA) t. This stabilizes the membrane potential, and prevented the cells from returning to resting membrane potential.