Quaternary Ammonium Compounds as Water Channel Blockers

Trapping of Organic Blockers by Closing of Voltage-dependent K+ Channels

Small organic molecules, like quaternary ammonium compounds, have long been used to probe both the permeation and gating of voltage-dependent K+ channels. For most K+ channels, intracellularly applied quaternary ammonium (QA) compounds such as tetraethylammonium (TEA) and decyltriethylammonium (C10) behave primarily as open channel blockers: they can enter the channel only when it is open, and ...

Kinetics of Tethering Quaternary Ammonium Compounds to K+ Channels

Polymeric maleimido-quaternary ammonium (QA) compounds have been shown to function as molecular tape measures when covalently tethered to external cysteine residues of a Shaker K(+) channel (Blaustein R.O., P.A. Cole, C. Williams, and C. Miller. 2000. Nat. Struct. Biol. 7:309-311). For sufficiently long compounds, the cysteine-maleimide tethering reaction creates a high concentration, at the ch...

Studies on tolerance to ganglionic blocking agents in man; reversal of depressor action of quaternary ammonium compounds.

Use-dependent blockers and exit rate of the last ion from the multi-ion pore of a K+ channel.

Quaternary ammonium blockers inhibit many voltage-activated potassium (K+) channels from the intracellular side. When applied to Drosophila Shaker potassium channels expressed in mammalian cells, these rapidly reversible blockers produced use-dependent inhibition through an unusual mechanism--they promoted an intrinsic conformational change known as C-type inactivation, from which recovery is s...

Bis-quaternary ammonium blockers as structural probes of the sarcoplasmic reticulum K+ channel

A series of n-alkyl-bis-alpha,omega-trimethylammonium (bisQn) compounds was synthesized, and their ability to block K+ currents through a K+ channel from sarcoplasmic reticulum was studied. K+ channels were inserted into planar phospholipid membranes, and single-channel K+ currents were measured in the presence of the blocking cations. These bisQn compounds block K+ currents only from the side ...