Referenced in: none

Automatically associated channels: Kv1.4

Title: Potent inhibition of native TREK-1 K+ channels by selected dihydropyridine Ca2+ channel antagonists.

Authors: Haiyan Liu, Judith A Enyeart, John J Enyeart

Journal, date & volume: J. Pharmacol. Exp. Ther., 2007 Oct , 323, 39-48

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/17622574

Abstract
Bovine adrenal zona fasciculata (AZF) cells express bTREK-1 background K+ channels that set the resting membrane potential. Whole-cell and single-channel patch-clamp recording were used to compare five Ca2+ channel antagonists with respect to their potency as inhibitors of native bTREK-1 K+ channels. The dihydropyridine (DHP) Ca2+ channel antagonists amlodipine and niguldipine potently and specifically inhibited bTREK-1 with IC50 values of 0.43 and 0.75 microM, respectively. The other Ca2+ channel antagonists, including the DHP nifedipine, the diphenyldiperazine flunarizine, and the cannabinoid anandamide were less potent, with IC50 values of 8.18, 2.48, and 5.07 microM, respectively. Additional studies with the highly prescribed antihypertensive amlodipine showed that inhibition of bTREK-1 by this agent was voltage-independent and specific. At concentrations that produced near complete block of bTREK-1, amlodipine inhibited voltage-gated Kv1.4 K+ and T-type Ca2+ currents in AZF cells by less than 10%. At the single-channel level, amlodipine reduced bTREK-1 open probability without altering the unitary conductance. The results demonstrate that selected DHP L-type Ca2+ channel antagonists potently inhibit native bTREK-1 K+ channels, whereas other Ca2+ channel antagonists also inhibit bTREK-1 at higher concentrations. Collectively, organic Ca2+ channel antagonists make up the most potent class of TREK-1 inhibitors yet described. Because TREK-1 K+ channels are widely expressed in the central nervous and cardiovascular systems, it is possible that some of the therapeutic or toxic effects of frequently prescribed drugs such as amlodipine may be due to their interaction with TREK-1 K+ rather L-type Ca2+ channels.