Abstract
Raloxifene is widely used in the treatment of postmenopausal osteoporosis and also has been shown to be cardioprotective. The effect of raloxifene on cardiac ion channels is not fully understood. The present study investigated whether raloxifene could affect the cloned hERG channel (I(hERG)) and recombinant human cardiac KCNQ1/KCNE1 channel (I(Ks)) stably expressed in HEK 293 cells using a patch-clamp technique. Raloxifene blocked I(hERG) with an IC(50) of 1.1 μM and decreased I(Ks) (IC(50): 4.8 μM) without affecting activation kinetics. In addition, raloxifene significantly decreased I(Na) (IC(50): 2.8 μM) in guinea pig ventricular myocytes. However, this drug (1 μM) did not increase QRS and QTc interval in isolated guinea pig hearts. These results demonstrate that raloxifene, despite its inhibitory action on delayed rectifier potassium currents, does not prolong ECG QTc interval, suggesting that raloxifene is likely a safe selective estrogen receptor modulator with less cardiac toxicity.
Copyright © 2010 Elsevier Ltd. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Delayed Rectifier Potassium Channels / antagonists & inhibitors*
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Delayed Rectifier Potassium Channels / metabolism
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Electrocardiography
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Ether-A-Go-Go Potassium Channels / antagonists & inhibitors
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Ether-A-Go-Go Potassium Channels / metabolism
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Female
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Guinea Pigs
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HEK293 Cells
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Humans
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KCNQ1 Potassium Channel / antagonists & inhibitors
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KCNQ1 Potassium Channel / metabolism
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Long QT Syndrome / chemically induced
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Male
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Myocytes, Cardiac / drug effects*
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Myocytes, Cardiac / metabolism
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Patch-Clamp Techniques
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Potassium Channels, Voltage-Gated / antagonists & inhibitors
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Potassium Channels, Voltage-Gated / metabolism
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Raloxifene Hydrochloride / pharmacology*
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Raloxifene Hydrochloride / toxicity
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Selective Estrogen Receptor Modulators / pharmacology*
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Selective Estrogen Receptor Modulators / toxicity
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Sex Characteristics
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Sodium Channels / metabolism*
Substances
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Delayed Rectifier Potassium Channels
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Ether-A-Go-Go Potassium Channels
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KCNE1 protein, human
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KCNQ1 Potassium Channel
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KCNQ1 protein, human
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Potassium Channels, Voltage-Gated
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Selective Estrogen Receptor Modulators
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Sodium Channels
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Raloxifene Hydrochloride