...why TEA in the pipette?

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Hss
Hss's picture
...why TEA in the pipette?

Hola

I saw that in many cases when calcium currents are recorded in neurons, people used TEA in the pipette, so I would like to know why? ...because now I have to do some recordings in neurons, for calcium currents and I´m looking for the best conditions to do it.

Thanks.

Bluejay
Bluejay's picture
Traditionally TEA is used at

Traditionally TEA is used at mM levels as a potassium channel blocker. The Sigma/RBI handbook lists TEA as an inhibitor of potassium channels including: 1) ATP-sensitive, 2) voltage gated, 3) Ca2+-Activated and 4) KCNQ. So perhaps it is used in your case to inhibit Ca2+ activated potassium channels.

Hss
Hss's picture
...it seems that TEA is for

...it seems that TEA is for block potassium channels, so it means that when potassium channels are blocked the calcium currents are better? ...why?

Thanks.

Fraser Moss
Fraser Moss's picture
You block the Ca activated

You block the Ca activated Potassium channels so that they do not get activated when you activate the calcium channels. Then the Ca Channel trace that you are trying to record is not contaminated by the currents from the Ca activated K channels.

hyunjoe
hyunjoe's picture
The TEA is a whole K-channels

The TEA is a whole K-channels blocker as described upper. Usually, to record the Ca-channels, you may inhibit all the outward currents, since it would "contaminate" the trace of inward current that you want to record (it is just that your negative trace that you want to may have a voltage-dependent - so not constant - offset of positive current). So if you want to get a good trace of inward current you HAVE TO inhibit the K-currents.

However, I have seen TEA used "in the pipette", but I didn't see much more results than using it only "extracellularly". You may get anyway a better inhibition of K-channels (by initiating the competition between the K+ and the TEA+ in the cell). I have been using that for measuring the persistent sodium current in neurons, but I didn't compare with another solution without TEA. The good thing by having it inside the pipette right at the start is that you don't have to put your TEA in the bath that can make your seal unstable...

Hope that helps

Hss wrote:

...it seems that TEA is for block potassium channels, so it means that when potassium channels are blocked the calcium currents are better? ...why?

Thanks.