Mechanism of hERG K + channel blockade by the fluoroquinolone antibiotic moxifloxacin
Abstract
The fluoroquinolone antibiotic moxifloxacin has been associated with the acquired long QT syndrome and is used as a positive control in the evaluation of the QT-interval prolonging potential of new drugs. In common with other QT-prolonging agents, moxifloxacin is known to inhibit the hERG potassium K+ channel, but at present there is little mechanistic information available on this action. This study was conducted in order to characterise the inhibition of hERG current (I(hERG)) by moxifloxacin, and to determine the role in drug binding of the S6 aromatic amino-acid residues Tyr652 and Phe656. hERG currents were studied using whole-cell patch clamp (at room temperature and at 35-37 degrees C) in an HEK293 cell line stably expressing hERG channels. Moxifloxacin reversibly inhibited currents in a dose-dependent manner. We investigated the effects of different voltage commands to elicit hERG currents on moxifloxacin potency. Using a 'step-ramp' protocol, the IC50 was 65 microM at room temperature and 29 microM at 35 degrees C. When a ventricular action potential waveform was used to elicit currents, the IC50 was 114 microM. Block of hERG by moxifloxacin was found to be voltage-dependent, occurred rapidly and was independent of stimulation frequency. Mutagenesis of the S6 helix residue Phe656 to Ala failed to eliminate or reduce the moxifloxacin-mediated block whereas mutation of Tyr652 to Ala reduced moxifloxacin block by approximately 66%. Our data demonstrate that…
Read the paper
Related studies
- Synthesis, In Vitro and In Silico Molecular Docking Studies of Novel Phthalimide–Pyrimidine Hybrid Analogues to Thalidomide as Potent Antitubercular Agents
- Exploring the inhibitory performance of expired moxifloxacin and norfloxacin on copper corrosion in saline environment
- Molecular investigation of antimicrobial peptides against Helicobacter pylori proteins using a peptide-protein docking approach
- Screening of novel narrow-spectrum benzofuroxan derivatives for the treatment of multidrug-resistant tuberculosis through in silico, in vitro, and in vivo approaches
- Synthesis, Characterization, Anticancer, Antioxidant, and In Silico Evaluation of Semicarbazides and Thiosemicarbazides
- Fast and accurate prediction of drug induced proarrhythmic risk with sex specific cardiac emulators
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.