ClassIIIantiarrhythmic drugs amiodarone and dronedarone impairK_IR2.1 backward trafficking

Abstract

Drug‐induced ion channel trafficking disturbance can cause cardiac arrhythmias. The subcellular level at which drugs interfere in trafficking pathways is largely unknown. KIR2.1 inward rectifier channels, largely responsible for the cardiac inward rectifier current (IK 1), are degraded in lysosomes. Amiodarone and dronedarone are class III antiarrhythmics. Chronic use of amiodarone, and to a lesser extent dronedarone, causes serious adverse effects to several organs and tissue types, including the heart. Both drugs have been described to interfere in the late‐endosome/lysosome system. Here we defined the potential interference in KIR2.1 backward trafficking by amiodarone and dronedarone. Both drugs inhibited IK 1 in isolated rabbit ventricular cardiomyocytes at supraclinical doses only. In HK‐KWGF cells, both drugs dose‐ and time‐dependently increased KIR2.1 expression (2.0 ± 0.2‐fold with amiodarone: 10 μM, 24 hrs; 2.3 ± 0.3‐fold with dronedarone: 5 μM, 24 hrs) and late‐endosomal/lysosomal KIR2.1 accumulation. Increased KIR2.1 expression level was also observed in the presence of Nav1.5 co‐expression. Augmented KIR2.1 protein levels and intracellular accumulation were also observed in COS‐7, END‐2, MES‐1 and EPI‐7 cells. Both drugs had no effect on Kv11.1 ion channel protein expression levels. Finally, amiodarone (73.3 ± 10.3% P < 0.05 at −120 mV, 5 μM) enhanced IKIR 2.1 upon 24‐hrs treatment, whereas dronedarone tended to increase IKIR 2.1 and it did not reach significance (43.8 ± 5.5%, P = 0.26 at −120 mV; 2 μM). We conclude that chronic amiodarone, and potentially also dronedarone, treatment can result in enhanced IK 1 by inhibiting KIR2.1 degradation.

Identification of a PEST Sequence in Vertebrate KIR2.1 That Modifies Rectification

“…Recordings were performed 24 h after transfection. In western blot experiments, HEK293T cells were grown on 60 mm tissue culture dishes and transfected using linear PEI as described earlier (Ji et al, 2017a). In immunofluorescence microscopy experiments, COS-7 cells were grown on Ø 15 mm coverslips, pre-coated with poly-L-lysine (Sigma-Aldrich), and transfected with K IR 2.1 (WT or ΔPEST) using Lipofectamine according to the manufacturer’s protocol.…”

“…COS-7 cells were stained essentially as described earlier (Ji et al, 2017a). Antibodies used were K IR 2.1 (1:250; Santa Cruz Biotechnology, Heidelberg, Germany, cat.…”

Cardiac Arrhythmias and Antiarrhythmic Drugs: An Autophagic Perspective

“…Class III antiarrhythmic drug amiodarone inhibits mTORC1 leading to stimulation of the autophagy pathway, which was explored in vitro (Balgi et al, 2009 ). In another in vitro study, we indicated lysosomal impairment by amiodarone and its synthetic analog dronedarone, which resulted in increased inward rectifier potassium channel K ir 2.1 expression and intracellular accumulation (Ji et al, 2017a ). The well-known drawback of amiodarone is its high incidence of side effects, including thyroid toxicity, pulmonary toxicity, hepatic toxicity, neurological toxicity, which seem to be related to the lifetime cumulative dose of the drug (Santangeli et al, 2012 ).…”

Emerging roles for multifunctional ion channel auxiliary subunits in cancer

“…I Kir is instead dictated by the electrochemical gradient and an increasing intracellular blocking of the pore when the membrane potential (E m ) > E K , resulting in an inward I K when E m < E K and an outward I K when E m > E k , which is progressively blocked as E m rises [ 197 ]. K ir channels are therefore important for maintenance of the hyperpolarised resting membrane potential and regulating activity in excitable cells, such as vascular smooth muscle [ 198 ], central neurons [ 199 ] and cardiomyocytes [ 200 ]. Subfamilies of K ir channels exist that are ATP-sensitive (K ATP channels; K ir 6. x ) and G-protein gated (G-protein inwardly rectifying K + channels- GIRKs; K ir 3. x ) [ 201 , 202 ].…”