DIgoxin mechanism

[yankees527]

Here I am again asking about drug mechanisms that Uworld mentions (wasnt expecting all these contradictions in uworld, but whatever).

We all know that digoxin increases intracellular sodium, but uworld and first aid mentions that it decreases calcium efflux, and does not increase calcium influx. According to sketchy and uptodate, it does the latter.

This is starting to get very annoying and I dont even know what to believe anymore.

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[chromuffin]

Here I am again asking about drug mechanisms that Uworld mentions (wasnt expecting all these contradictions in uworld, but whatever).

We all know that digoxin increases intracellular sodium, but uworld and first aid mentions that it decreases calcium efflux, and does not increase calcium influx. According to sketchy and uptodate, it does the latter.

This is starting to get very annoying and I dont even know what to believe anymore.

Digoxin inhibits the Na-K ATPase right? So then you can't get Na efflux from the cell. This causes the Na-Ca antiporter to decrease activity since this antiporter causes Ca efflux. Thus, you don't get Ca efflux because the antiporter isn't working. This causes increased intracellular Ca levels, which prevents influx too (because the Ca concentration gradient is set up for Ca efflux). So, to answer your question, digoxin prevents both.

Ca efflux prevented: Na-Ca antiporter doesnt work since Na levels high intracellular.
Ca influx prevented: intracellular Ca levels are elevated

 

[yankees527]

Digoxin inhibits the Na-K ATPase right? So then you can't get Na efflux from the cell. This causes the Na-Ca antiporter to decrease activity since this antiporter causes Ca efflux. Thus, you don't get Ca efflux because the antiporter isn't working. This causes increased intracellular Ca levels, which prevents influx too (because the Ca concentration gradient is set up for Ca efflux). So, to answer your question, digoxin prevents both.

Ca efflux prevented: Na-Ca antiporter doesnt work since Na levels high intracellular.
Ca influx prevented: intracellular Ca levels are elevated

I understand how it can be both, but uworld specifically said in their explanation it does not cause calcium influx.
End result either way is increased calcium, but i just dont want to get stumped on a question about it because of semantics

 

[chromuffin]

I understand how it can be both, but uworld specifically said in their explanation it does not cause calcium influx.
End result either way is increased calcium, but i just dont want to get stumped on a question about it because of semantics

I wouldn't worry about semantics. Understand the concept, not the wording. Questions like this would likely be eliminated. I'm curious what QID this is..

 

[yankees527]

I wouldn't worry about semantics. Understand the concept, not the wording. Questions like this would likely be eliminated. I'm curious what QID this is..

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