Cardiac inward rectifier channels belong to three different classes of the KIR channel protein family.
The KIR2.x proteins generate the classical inward rectifier current, IK1, while KIR
3 and KLIR6 members are
responsible for the acetylcholine responsive and ATP sensitive inward rectifier currents IKAch and IKATP,
respectively. Aberrant function of these channels has been correlated with severe cardiac arrhythmias,
indicating their significant contribution to normal cardiac electrophysiology. A common feature of inward
rectifier channels is their dependence on the lipid phosphatidyl-4,5-bisphospate (PIP2) interaction for functional
activity. Cationic amphiphilic drugs (CADs) are one of the largest classes of pharmaceutical compounds.
Several widely used CADs have been associated with inward rectifier current disturbances, and recent
evidence points to interference of the channel-PIP2 interaction as the underlying mechanism of action. Here,
we will review how six of these well known drugs, used for treatment in various different conditions, interfere in
cardiac inward rectifier functioning. In contrast, KIR channel inhibition by the anionic anesthetic thiopental is
achieved by a different mechanism of channel-PIP2 interference. We will discuss the latest basic science
insights of functional inward rectifier current characteristics, recently derived KIR channel structures and
specific PIP2-receptor interactions at the molecular level and provide insight in how these drugs interfere in the
Keywords: Bupivacaine, cardiac inward rectifier, carvedilol, IKATP, IKAch, IK1, KIR6, KIR3, KIR2, mefloquine,
mepyramine, molecular modeling, quinacrine, structure, tamoxifen, thiopental.
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