Dequalinium: a novel, high-affinity blocker of CNGA1 channels.

Article Details

Citation

Rosenbaum T, Islas LD, Carlson AE, Gordon SE

Dequalinium: a novel, high-affinity blocker of CNGA1 channels.

J Gen Physiol. 2003 Jan;121(1):37-47.

PubMed ID
12508052 [ View in PubMed
]
Abstract

Cyclic nucleotide-gated (CNG) channels have been shown to be blocked by diltiazem, tetracaine, polyamines, toxins, divalent cations, and other compounds. Dequalinium is an organic divalent cation which suppresses the rat small conductance Ca(2+)-activated K(+) channel 2 (rSK2) and the activity of protein kinase C. In this study, we have tested the ability of dequalinium to block CNGA1 channels and heteromeric CNGA1+CNGB1 channels. When applied to the intracellular side of inside-out excised patches from Xenopus oocytes, dequalinium blocks CNGA1 channels with a K(1/2) approximately 190 nM and CNGA1+CNGB1 channels with a K(1/2) approximately 385 nM, at 0 mV. This block occurs in a state-independent fashion, and is voltage dependent with a zdelta approximately 1. Our data also demonstrate that dequalinium interacts with the permeant ion probably because it occupies a binding site in the ion conducting pathway. Dequalinium applied to the extracellular surface also produced block, but with a voltage dependence that suggests it crosses the membrane to block from the inside. We also show that at the single-channel level, dequalinium is a slow blocker that does not change the unitary conductance of CNGA1 channels. Thus, dequalinium should be a useful tool for studying permeation and gating properties of CNG channels.

DrugBank Data that Cites this Article

Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
DequaliniumcGMP-gated cation channel alpha-1ProteinHumans
Unknown
Blocker
Details