Killing K Channels with TEA (dekalificationychannel blockydecyltriethylammoniumytetraethylammonium)

Tetraethylammonium (TEA1) is widely used for reversible blockade of K channels in many preparations. We noticed that intracellular perfusion of voltage-clamped squid giant axons with a solution containing K1 and TEA1 irreversibly decreased the potassium current when there was no K1 outside. Five minutes of perfusion with 20 mM TEA1, followed by removal of TEA1, reduced potassium current to <5% of its initial value. The irreversible disappearance of K channels with TEA1 could be prevented by addition of > 10 mM K1 to the extracellular solution. The rate of disappearance of K channels followed first-order kinetics and was slowed by reducing the concentration of TEA1. Killing is much less evident when an axon is held at 2110 mV to tightly close all of the channels. The longer-chain TEA1 derivative decyltriethylammonium (C101) had irreversible effects similar to TEA1. External K1 also protected K channels against the irreversible action of C101. It has been reported that removal of all K1 internally and externally (dekalification) can result in the disappearance of K channels, suggesting that binding of K1 within the pore is required to maintain function. Our evidence further suggests that the crucial location for K1 binding is external to the (internal) TEA1 site and that TEA1 prevents refilling of this location by intracellular K1. Thus in the absence of extracellular K1, application of TEA1 (or C101) has effects resembling dekalification and kills the K