How does tetraethylammonium affect the restig membrane potential?

Answer 1

Tetrodotoxin (TTX) completely prevents action potentials from generating peripherally. This can be fatal because it causes muscle paralysis, including those responsible for respiration. The way TTX does this is by blocking sodium channels, thereby preventing sodium ions from entering the cell, which in turn prevents membrane depolarisation.

Answer 2

TEA blocks the voltage gated potassium channels. But it does not have any effect on the voltage gated sodium channels. So neurons can reach depolarize but cannot re-polarize as TEA blocks the action of the voltage gated potassium channels. So, sodium enters the cells until membrane potential reaches +60mV. At this point the Na+/K+ ATPase starts to act and re-polarizes the cell.