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jwong3328

Effects of High K+ concentration

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hey guys, im a first year pharm student and ive run into a lil bit of a pickle here.

 

What are the effects on action potentials for having high concentrations of K+ in extracellular fluid?

 

As I understand it, during an action potential there is Na+ influx which depolarises (makes more positive) the cell. Once threshold membrane potential is reached, an AP occurs. Then there is a K+ efflux to repolarise (more -ve) the cell. If there is increased concentration of K+ on the outside, the rate of K+ efflux would decrease so repolarisation will occur more slowly.

THIS WILL MEAN AP OCCUR LESS FREQUENTLY / SLOWLY.

 

So, the inside of the cell will be more positive than before because less K+ has left the cell. This means the resting membrane potential is closer to threshold. THIS MEAN AP CAN OCCUR MORE EASILY.

 

can someones please confirm or correct my above statements? Im just a first year student so im a newb at this stuff but ill try contribute to this forum whenever i can.

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I'm a former cardiology technician, early 90's, and though it's been awhile, I *think* you have it correct. In my world back then I would have perhaps told a patient that because his K+ was high, his heart was "irritable", making him subject to various tachycardias or wide-QRS complex rhythms. The devil may be in the details though, and it's been awhile for me. Someone else may have better information.

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