title: Phlorizin prevents electrically-induced ventricular tachyarrhythmia during ischemia in langendorff-perfused guinea-pig hearts.
abstract: Phlorizin is a type of flavonoids and has a peroxynitrite scavenging effect. This study aimed to elucidate the effects of phlorizin on ischemia-induced ventricular tachyarrhythmia (VT). Optical signals from the epicardial surface of the ventricle or left ventricular end diastolic pressure (LVEDP) were recorded during acute global ischemia in 42 Langendorff-perfused guinea pig hearts. Experiments were performed in the control condition and in the presence of phlorizin or N-2-mercaptopropionylglycine (2-MPG), a peroxynitrite scavenger, respectively. Mean action potential duration at 20 min of ischemia did not differ among the three interventions. Impulse conduction time-dependently slowed during 20 min of ischemia in the control. Phlorizin but not 2-MPG improved the ischemic conduction slowing at 15 and 20 min of ischemia. Programmed stimulation induced VT at 20 min of ischemia in the control and in the presence of 2-MPG but not in the presence of phlorizin (p<0.05). LVEDP was increased during 30 min of ischemia in the control and in the presence of 2-MPG but not in the presence of phlorizin. These results indicate that phlorizin prevents VT through the improvement of impulse conduction slowing during ischemia. Phlorizin may be more useful for ischemia-induced VT than 2-MPG.
authors.affiliation: Department of Molecular and Cellular Pharmacology, Iwate Medical University School of Pharmaceutical Sciences.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Hirose
authors.forename: Toshihide
authors.initials: T
authors.lastname: Shibazaki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakada
authors.forename: Toshihide
authors.initials: T
authors.lastname: Kashihara
authors.forename: Shiharu
authors.initials: S
authors.lastname: Yano
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Isaji
authors.forename: Naoko
authors.initials: N
authors.lastname: Matsushita
authors.forename: Eiichi
authors.initials: E
authors.lastname: Taira
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Yamada
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation; D004562:Electrocardiography; D004566:Electrodes; D006168:Guinea Pigs; D006329:Heart Conduction System / Q000187:drug effects; D017202:Myocardial Ischemia / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D010477:Perfusion; D010695:Phlorhizin / Q000008:administration & dosage / Q000627:therapeutic use*; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D016277:Ventricular Function, Left / Q000187:drug effects; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D000889:Anti-Arrhythmia Agents; D010695:Phlorhizin; D002118:Calcium