The membrane permeable calcium chelator BAPTA-AM directly blocks human ether a-go-go-related gene potassium channels stably expressed in HEK 293 cells

Tang, Qiang; Jin, Man-Wen; Xiang, Jizhou; Dong, Min-Qing; Sun, Hai‐Ying; Lau, Chi-Wai; Li, Gui-Rong

doi:10.1016/j.bcp.2007.07.042

Cited by 57 publications

(48 citation statements)

References 47 publications

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“…This finding may indicate that the Nav1.5 channels have a window region in which the steady-state activation curve and inactivation curve overlap. Similar phenomena have also been observed with respect to the effects of other open channel blockers on other channels; for example, neferine interacts with both open and inactive Kv4.3 channels [29] , BAPTA-AM interacts with both open and inactive hERG channels [30] , and carvedilon and pergolide interact with both open and inactive Kv1.5 channels [31,32] . Mammalian species express nine functional voltage-gated Na + channels.…”

Section: Discussionmentioning

confidence: 59%

Inhibitory effects of hesperetin on Nav1.5 channels stably expressed in HEK 293 cells and on the voltage-gated cardiac sodium current in human atrial myocytes

Wang

Zhang

et al. 2016

Acta Pharmacol Sin

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Aim: Voltage-gated sodium channels composed of a pore-forming α subunit and auxiliary β subunits are responsible for the upstroke of the action potential in cardiac myocytes. The pore-forming subunit of the cardiac sodium channel Nav1.5, which is encoded by SCN5A, is the main ion channel that conducts the voltage-gated cardiac sodium current (I Na ) in cardiac cells. The current study sought to investigate the inhibitory effects of hesperetin on human cardiac Nav1.5 channels stably expressed in human embryonic kidney 293 (HEK 293) cells and on the voltage-gated cardiac sodium current (I Na ) in human atrial myocytes. Methods: The effects of hesperetin on human cardiac Nav1.5 channels expressed in HEK 293 cells and on cardiac Na + currents in human atrial myocytes were examined through whole-cell patch-clamp techniques. Results: Nav1.5 currents were potently and reversibly suppressed in a concentration-and voltage-dependent manner by hesperetin, which exhibited an IC 50 of 62.99 μmol/L. Hesperetin significantly and negatively shifted the voltage-dependent activation and inactivation curves. Hesperetin also markedly decelerated Nav1.5 current inactivation and slowed the recovery from Nav1.5 channel inactivation. The hesperetin-dependent blockage of Nav1.5 currents was frequency-dependent. Hesperetin also potently and reversibly inhibited Na + current (I Na ) in human atrial myocytes, consistently with its effects on Nav1.5 currents in HEK 293 cells. Conclusion: Hesperetin is a potent inhibitor of I Na in human atrial myocytes and Nav1.5 channels expressed in human embryonic kidney 293 cells. Hesperetin probably functions by blocking the open state and the inactivated state of these channels.

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Section: Discussionmentioning

confidence: 59%

Inhibitory effects of hesperetin on Nav1.5 channels stably expressed in HEK 293 cells and on the voltage-gated cardiac sodium current in human atrial myocytes

Wang

Zhang

et al. 2016

Acta Pharmacol Sin

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“…Established HEK 293 cell lines stably expressing the hERG (human ether-a-go-go related gene) channel gene 15 and recombinant human cardiac KCNQ1/KCNE1 channel current (I Ks ) 16 were maintained separately in DMEM (Invitrogen, Carlsbad, Calif) supplemented with 10% fetal bovine serum and containing 400 g/mL G418 (for hERG channels) or 100 g/mL hygromycin (for I Ks ).…”

Section: Cell Line Culturementioning

confidence: 99%

Acacetin, a Natural Flavone, Selectively Inhibits Human Atrial Repolarization Potassium Currents and Prevents Atrial Fibrillation in Dogs

et al. 2008

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Background-The development of atrium-selective antiarrhythmic agents is a current strategy for inhibiting atrial fibrillation (AF). The present study investigated whether the natural flavone acacetin from the traditional Chinese medicine Xuelianhua would be an atrium-selective anti-AF agent. Methods and Results-The effects of acacetin on human atrial ultrarapid delayed rectifier K ϩ current (I Kur ) and other cardiac ionic currents were studied with a whole-cell patch technique. Acacetin suppressed I Kur and the transient outward K ϩ current (IC 50 3.2 and 9.2 mol/L, respectively) and prolonged action potential duration in human atrial myocytes. The compound blocked the acetylcholine-activated K ϩ current; however, it had no effect on the Na ϩ current, L-type Ca 2ϩ current, or inward-rectifier K ϩ current in guinea pig cardiac myocytes. Although acacetin caused a weak reduction in the hERG and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells, it did not prolong the corrected QT interval in rabbit hearts. In anesthetized dogs, acacetin (5 mg/kg) prolonged the atrial effective refractory period in both the right and left atria 1 to 4 hours after intraduodenal administration without prolongation of the corrected QT interval, whereas sotalol at 5 mg/kg prolonged both the atrial effective refractory period and the corrected QT interval. Acacetin prevented AF induction at doses of 2.5 mg/kg (50%), 5 mg/kg (85.7%), and 10 mg/kg (85.7%). Sotalol 5 mg/kg also prevented AF induction (60%). Conclusions-The present study demonstrates that the natural compound acacetin is an atrium-selective agent that prolongs the atrial effective refractory period without prolonging the corrected QT interval and effectively prevents AF in anesthetized dogs after intraduodenal administration. These results indicate that oral acacetin is a promising atrium-selective agent for the treatment of AF.

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“…CASQ2 may exert its effects on hERG channels by chelation and thereby effective reduction of the free intracellular calcium. Indeed, Tang et al showed recently that hERG channels are inhibited by the Ca 2+ chelators BAPTA and, to a lesser extend, EGTA [21]. To explore whether the CASQ2 inhibition of hERG channels depends on the free intracellular Ca 2+ concentration we tested inhibition of hERG in the presence of the Ca 2+ chelator BAPTA.…”

Section: Resultsmentioning

confidence: 99%

“…Xenopus laevis oocytes were harvested in accordance with German laws as described previously [21]. Animals were ethyl 3-aminobenzoate methanesulfonic acid-(tricaine) anesthetized, ovarian lobes were removed from Xenopus laevis and digested with collagenase (Type II, Worthington, 1 mg/ml in calcium-free Barth's solution) for about 120 min.…”

Section: Electrophysiologymentioning

confidence: 99%

Modulation of Human Ether A Gogo Related Channels by CASQ2 Contributes to Etiology of Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Eckey

Strutz‐Seebohm

Katz

et al. 2010

Cell Physiol Biochem

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Rationale - The plateau phase of the ventricular action potential is the result of balanced Ca²⁺ influx and K⁺ efflux. The action potential is terminated by repolarizing K⁺ currents. Under β-adrenergic stimulation, both the Ca²⁺-influx and the delayed rectifier K⁺ currents I_K are stimulated to adjust the cardiac action potential duration to the enhanced heart rate and to ascertain adequate increase in net Ca²⁺ influx. Intracellularly, a Calsequestrin2 (CASQ2)-ryanodine receptor complex serves as the most effective Ca²⁺ reservoir/release system to aid the control of intracellular Ca²⁺ levels. Currently, it is unclear if disease-associated CASQ2 gene variants alter intracellular free Ca²⁺ concentrations and if cardiac ion channels are affected by it. Objective – The goal of this study is to test if CASQ2 determines intracellular free Ca²⁺ concentrations and to identify cardiac ion channels that are affected by it. Further, we aim to study disease-associated CASQ2 gene variants in this context. Methods and Results - Here, we study the effects of the CASQ2 mutations R33Q, F189L, and D307H, located in highly conserved regions, on the functions of cardiac potassium channels in Xenopus oocytes using two electrode voltage clamp. As a result, CASQ2 wild type and CASQ2-mutants modulated hERG functions differently. Free Ca²⁺ measurements and molecular dynamics simulations imply alterations in Ca²⁺ buffer capacity paralled by changes in the dynamic behavior of the CASQ2-mutants compared to CASQ2 wild type. Conclusions - These in vitro and in silico data suggest a regulatory role of CASQ2 on cytosolic Ca²⁺ and hERG channels which may contribute to the etiology of CPVT.

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The membrane permeable calcium chelator BAPTA-AM directly blocks human ether a-go-go-related gene potassium channels stably expressed in HEK 293 cells

Cited by 57 publications

References 47 publications

Inhibitory effects of hesperetin on Nav1.5 channels stably expressed in HEK 293 cells and on the voltage-gated cardiac sodium current in human atrial myocytes

Inhibitory effects of hesperetin on Nav1.5 channels stably expressed in HEK 293 cells and on the voltage-gated cardiac sodium current in human atrial myocytes

Acacetin, a Natural Flavone, Selectively Inhibits Human Atrial Repolarization Potassium Currents and Prevents Atrial Fibrillation in Dogs

Modulation of Human Ether A Gogo Related Channels by CASQ2 Contributes to Etiology of Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

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