IndraLab

Statements



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"One notable example is verapamil, which inhibits hERG in vitro but does not cause QT prolongation in vivo because of its additional calcium channel blocking properties. xref Although it inhibits hERG in vitro and causes QT prolongation, ranolazine is similarly free from proarrhythmia likely due to its additional late I Na channel blocking properties. xref The traditional gold standard is to measure I Kr in these heterologous expression systems by manual patch clamp, which is low throughput."

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"In our experiments, verapamil caused high-affinity block of HERG current (IC50 = 143.0 nmol/L), a value close to those reported for verapamil block of L-type Ca2+ channels, whereas diltiazem weakly blocked HERG current (IC50 = 17.3 micromol/L), and nifedipine did not block HERG current."

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"The classic example of this is verapamil, which can effectively inhibit hERG channels but does not significantly alter cardiac repolarization, QT interval or possess any TdP liability ( Pugsley et al.[MISSING/INVALID CREDENTIALS: limited to 200 char for Elsevier]"

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"When expressed in transfected COS cells, HERG is blocked in a concentration dependent manner by bepridil (EC50 = 0.55 microM), verapamil (EC50 = 0.83 microM), and mibefradil (EC50 = 1.43 microM), whereas nitrendipine and diltiazem have negligible effects."

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"The treatment of the cells with hERG channel inhibitors such as nifekalant, E-4031, cisapride, terfenadine, and verapamil, recovered the prolonged AP and dose-dependently facilitated cell death upon ES."

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"Verapamil also produces high-affinity blockade of hERG currents, with an IC 50 of 143.0 nmol/L, close to its IC 50 for blockade of L-type calcium channels."

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"An example is shown in XREF_FIG, hERG tail currents were blocked by verapamil in a concentration dependent manner with an IC 50 value of 0.94 muM."

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"For example, verapamil, which blocks both the HERG channel and a calcium channel, has a lower risk than expected from targeting the HERG channel alone."

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"Verapamil is not associated with QT prolongation and TdP in humans, but inhibits hERG with an IC 50 of 0.94 muM (XREF_FIG and XREF_TABLE)."

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"However, as verapamil blocks cardiac calcium channels -- its primary mechanism, leading to QT shortening -- as well as hERG, the net effect on cardiac action potential duration is not markedly changed."

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"Verapamil, for example, produces strong hERG inhibition without prolonging the QT interval in both animals and humans."

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"Verapamil inhibits both hERG and calcium channels at therapeutic concentrations and does not induce a prolongation of the cardiac AP (e.g. ( xref ))."

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"Verapamil was predicted to possibly cause bladder disorders and hERG channel inhibition."

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"WT HERG is blocked in a concentration dependent manner by verapamil (half-maximal inhibition concentration [IC (50)] = 5.1 micromol/L), and the steady state activation and inactivation parameters are shifted to more negative values."

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"Besides affecting the calcium ion influx, verapamil also inhibits the hERG protein, similar to sotalol, but it does not increase the QT interval because the inhibition of both channels compensates [XREF_BIBR]."

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"While quinidine, which blocks hERG, calcium and late sodium currents, and verapamil, which blocks hERG and calcium currents, are multichannel blockers, only quinidine was found to be associated with pro arrhythmic risk."

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"Verapamil and vanoxerine (GBR12909) which produce direct block of hERG current do not inhibit trafficking of wild type hERG after overnight exposure."

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"Likewise, verapamil enantiomers that blocked the L-type Ca 2+ channels also blocked the K + hERG1 channels, but they had equal potencies of inhibition when tested in Xenopus oocytes."

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"For instance, verapamil inhibits hERG1 channels at clinically relevant concentrations, but it has no known risk for TdP due to its concomitant blockade of the depolarizing inward calcium current ( I Ca,L , through blockade of the calcium channel subunit Cav1.2), which alleviates the effects of reduced I Kr outward current xref , xref ."

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"Verapamil preferentially binds to and blocks open HERG channels."

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"Verapamil inhibits both hERG and calcium channels at therapeutic concentrations and does not induce a prolongation of the cardiac AP (e.g.)."

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"Verapamil blocks both hERG and Cav 1.2 (I CaL)."

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"Dofetilide, cisapride, sotalol, terfenadine and verapamil blocked hERG channels at 37degreesC with an IC50 of 7nM, 18nM, 343muM, 165nM and 214nM, respectively."

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"This study investigated the mechanism by which verapamil, which blocks 10R1, l-type Ca2+ channel and the HERG channel, blocks ATP sensitive K+ (K (ATP)) channels."

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"Dose response relationship characterizations of verapamil and rBeKm-1 blockage of hERG currents provided IC (50) values similar to values reported in the literature."

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"Verapamil blocks HERG channel by the helix residue Y652 and F656 in the S6 transmembrane domain."

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"HERG is blocked by bepridil (EC50 = 0.55 microM), verapamil (EC50 = 0.83 microM) and mibefradil (EC50 = 1.43 microM), whereas nitrendipine and diltiazem have negligible effects."

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"These properties are compared with four known HERG channel blockers including verapamil, cisapride, ketoconazole and dofetilide in the XREF_TABLE."

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"In some cases, compounds block hERG channels without prolonging the QT interval; for example, Verapamil blocks hERG potently, but does not prolong QT, probably due to the fact that this compound also [MISSING/INVALID CREDENTIALS: limited to 200 char for Elsevier]"

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"At clinically relevant concentrations, verapamil blocked hCav1.2 and hERG, as did vanoxerine and bepridil both of which also blocked hNav1.5."

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"The similar " crossover " on HERG tail currents has been reported for some known HERG channel blockers including the antiarrhythmics quinidine (Sanchez-Chapula et al., 2003) and verapamil, nervous system stimulant cocaine and some other quaternary ammonium compounds on the shaker potassium channels."

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"In addition to blocking L-type Ca 2+ channels, verapamil has been found to block the hERG channel by binding to the helix residue Y652 and F656 in the S6 transmembrane domain."

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"Verapamil block of HERG channels was use and frequency dependent, and verapamil unbound from HERG channels at voltages near the normal cardiac cell resting potential or with drug washout."

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"These include false positives such as verapamil that are not cardiotoxic but block the hERG channel, as well as false negatives such as alfuzosin, which do not bind hERG but elicit QT prolongation through interactions with other ion channels XREF_BIBR, XREF_BIBR."

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"One notable example is verapamil, which inhibits hERG in vitro but does not cause QT prolongation in vivo because of its additional calcium channel blocking properties."

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"N-methyl-verapamil, a membrane-impermeable, permanently charged verapamil analogue, blocked HERG channels only when applied intracellularly."

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"Verapamil causes strong hERG potassium channel block, and even more potent L-type calcium channel block (XREF_FIG)."

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"Verapamil blocked hERG and hCav 1.2 in vitro at clinically relevant concentrations and showed no proarrhythmia markers in either experiments or simulations."

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"Verapamil, for instance, is a potent blocker of hERG repolarising current, but does not prolong the QT interval or cause TdP due to compensatory block of calcium channel depolarising current (Fauchier[MISSING/INVALID CREDENTIALS: limited to 200 char for Elsevier]"

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"The verapamil metabolites D620 and D617 did not block HERG induced currents at concentrations of up to 30 microM (n = 3)."

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"The ranolazine level obtained showed increased trough and peak levels, but the patient developed increasing episodes of TdP, which we attributed to high-affinity block of hERG by verapamil (XREF_TABLE)."

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"Neither verapamil nor dofetilide inhibited trafficking of wild type hERG."