In reference to the synapse between a pre and post synaptic membrane, how does S

Question

In reference to the synapse between a pre and post synaptic membrane, how does Serotonin effect Potassium.My professor told us that in the axon terminus serotonin will block Potassium from leaving because the inside of the terminus is -70 and if Potassium leaves that -70 would become even more negative and cause a decrease in the number of neurotransmitters released. But the membrane potential for Potassium is -94.2 so I was thinking the -70 would become more positive if the Potassium left. Am I supposed to be looking at the cytosolic and interstitial numbers for potassium instead?

Explanation / Answer

First thing to mention is that Serotonin is excitatory neurotransmitter, means it cause depolarization in membrane when it bind to its receptoras present on post synaptic membrane.And mechanism of action of Serotionin is activation and opening of Na+ ions channels resulting influx of Na+ ions resulting in more positive mebrane potential and when it reach to threshhold level generate action potential .

then after fraction of second Na+ ion channel get inactivated simultaneously opening of K+ ion channels automatically lead to efflux of K+ ions resulting in more polarization means more negative potential.

but the serotonin regulates directly only on Na+ ion channels , yet their is not well established report on direct action of serotonin on K+ ion channels.

and in normal condition K+ leaky channels remains always open leading to slow efflux of K+ ions , but this loss of ions is compensated by Na+-K+ pumps resulting the resting membrane potential which is -70.

briefly we can say that serotonin doesnot have any direct effect on K+ ion channels.

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