title: Pronounced effects of HERG-blockers E-4031 and erythromycin on APD, spatial APD dispersion and triangulation in transgenic long-QT type 1 rabbits.
abstract: BACKGROUND
  Prolongation of action potential duration (APD), increased spatial APD dispersion, and triangulation are major factors promoting drug-induced ventricular arrhythmia. Preclinical identification of HERG/IKr-blocking drugs and their pro-arrhythmic potential, however, remains a challenge. We hypothesize that transgenic long-QT type 1 (LQT1) rabbits lacking repolarizing IKs current may help to sensitively detect HERG/IKr-blocking properties of drugs.
  
  
  METHODS
  Hearts of adult female transgenic LQT1 and wild type littermate control (LMC) rabbits were Langendorff-perfused with increasing concentrations of HERG/IKr-blockers E-4031 (0.001-0.1 µM, n=9/7) or erythromycin (1-300 µM, n=9/7) and APD, APD dispersion, and triangulation were analyzed.
  
  
  RESULTS
  At baseline, APD was longer in LQT1 than in LMC rabbits in LV apex and RV mid. Erythromycin and E-4031 prolonged APD in LQT1 and LMC rabbits in all positions. However, erythromycin-induced percentaged APD prolongation related to baseline (%APD) was more pronounced in LQT1 at LV base-lateral and RV mid positions (100 µM, LQT1, +40.6 ± 9.7% vs. LMC, +24.1 ± 10.0%, p<0.05) and E-4031-induced %APD prolongation was more pronounced in LQT1 at LV base-lateral (0.01 µM, LQT1, +29.6 ± 10.6% vs. LMC, +19.1 ± 3.8%, p<0.05) and LV base-septal positions. Moreover, erythromycin significantly increased spatial APD dispersion only in LQT1 and increased triangulation only in LQT1 in LV base-septal and RV mid positions. Similarly, E-4031 increased triangulation only in LQT1 in LV apex and base-septal positions.
  
  
  CONCLUSIONS
  E-4031 and erythromycin prolonged APD and increased triangulation more pronouncedly in LQT1 than in LMC rabbits. Moreover, erythromycin increased APD dispersion only in LQT1, indicating that transgenic LQT1 rabbits could serve as sensitive model to detect HERG/IKr-blocking properties of drugs.
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Ziupa
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Beck
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Gerlind
authors.initials: G
authors.lastname: Franke
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Perez Feliz
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Hartmann
authors.affiliation: Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America.
authors.forename: Gideon
authors.initials: G
authors.lastname: Koren
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Zehender
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Brunner
authors.affiliation: Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany.
authors.forename: Katja E
authors.initials: KE
authors.lastname: Odening
mesh_terms: D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D004917:Erythromycin / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D008133:Long QT Syndrome / Q000188:drug therapy* / Q000503:physiopathology; D010880:Piperidines / Q000494:pharmacology* / Q000627:therapeutic use; D011725:Pyridines / Q000494:pharmacology* / Q000627:therapeutic use; D011817:Rabbits
chemical_list: D010880:Piperidines; D011725:Pyridines; C063968:E 4031; D004917:Erythromycin