Cesium for K, but what for Na channels?

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gio
gio's picture
Cesium for K, but what for Na channels?

Hi everyone,
a stupid question on electrophysiology: why do we use Cs to block K channels and therefore isolate Na currents and do not do the same when studying K channels? I mean, why don't we use something to block Na channels and isolate therefore K currents?
thanks
g