Acetylcholine is both an excitatory and inhibitory ligand depending on the location of its receptor. What does acetylcholine do that makes it "Excitatory"?

Question

A. It opens k+ion channels when it binds to its receptors

B. It causes a cell membrane to hyperpolarize

C. It causes a cell membrane to depolarize and produce excitatory post synaptic potentials

Im pretty sure its C. But need a better explanation.

Answer 1

Acetylcholine is excitatory at the neuromuscular junction in skeletal muscles. The receptors here are actually ion channels. When the acetylcholine binds they open allowing Na ions to move into the cell and potassium ions to move out of the cell. Since there are more Na ions flowing in than potassium ions flowing out of the cell, the net effect is depolarizing.

I hope this helped and if you have any more questions. I'll be happy to answer!