Bepridil, an antiarrhythmic drug, opens mitochondrial KATP channels, blocks sarcolemmal KATP channels, and confers cardioprotection.

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Sato T, Costa AD, Saito T, Ogura T, Ishida H, Garlid KD, Nakaya H

Bepridil, an antiarrhythmic drug, opens mitochondrial KATP channels, blocks sarcolemmal KATP channels, and confers cardioprotection.

J Pharmacol Exp Ther. 2006 Jan;316(1):182-8. Epub 2005 Sep 20.

PubMed ID

16174795 [ View in PubMed

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Abstract

Bepridil, which is clinically useful in the treatment of arrhythmias, has been reported to inhibit sarcolemmal ATP-sensitive K(+) (sarcK(ATP)) channels. However, the effect of bepridil on mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channels remains unclear. The objective of the present study was to determine whether bepridil activates mitoK(ATP) channels and confers cardioprotection. SarcK(ATP) channels composed of Kir6.2+SUR2A in human embryonic kidney (HEK) 293 cells were examined using the patch-clamp technique. Flavoprotein fluorescence in guinea pig ventricular cells and matrix volume in isolated rat heart mitochondria were measured to assay mitoK(ATP) channel activity. Mitochondrial Ca(2+) concentration ([Ca(2+)](m)) was measured by loading cells with rhod-2 fluorescence. Coronary-perfused guinea pig ventricular muscles were subjected to 35-min no-flow ischemia followed by 60-min reperfusion. Bepridil (10 microM) completely inhibited the pinacidil-induced Kir6.2+SUR2A channel current expressed in HEK 293 cells. Bepridil reversibly oxidized the flavoprotein and increased mitochondrial matrix volume in a concentration-dependent manner. Furthermore, bepridil significantly attenuated the ouabain-induced increase of [Ca(2+)](m). Pretreatment with bepridil for 5 min before ischemia improved the recovery of developed tension measured after 60 min of reperfusion. These effects of bepridil were abolished by the mitoK(ATP) channel blocker 5-hydroxydecanoate (500 microM) and by the nonselective K(ATP) channel blocker glisoxepide (10 microM). Our results indicate that bepridil is an opener of mitoK(ATP) channels but an inhibitor of sarcK(ATP) channels and exerts a direct cardioprotective effect on native cardiac myocytes. This is the first report of a unique modulator of K(ATP) channels; bepridil would be expected to mitigate ischemic injury while blunting arrhythmias.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Gliquidone	ATP-sensitive inward rectifier potassium channel 8	Protein	Humans	Yes	Inhibitor	Details
Glisoxepide	ATP-sensitive inward rectifier potassium channel 8	Protein	Humans	Yes	Inhibitor	Details