title: Defibrillatory action of glibenclamide is independent from ATP-sensitive K+ channels and free radicals.
abstract: This study investigated whether glibenclamide exerts a defibrillatory action and if this action is mediated by a blockade of ATP-sensitive K+ channels (K(ATP)) or by an anti-free radical mechanism. Aerobically perfused isolated rat hearts were subjected to 10 min of pacing-induced ventricular fibrillation (VF) followed by 10 min of perfusion without pacing (post-VF period), in the presence of solvent (controls), 1 microM K(ATP) blocker glibenclamide, 10 microM K(ATP) opener cromakalim, and their combination, respectively. In controls, pacing-induced VF caused a significant deterioration in cardiac function in the post-VF period. Spontaneous defibrillation was 42%. Glibenclamide improved post-VF cardiac function and resulted in 100% (P < 0.05) spontaneous defibrillation. Cromakalim did not significantly affect post-VF cardiac function and the incidence of spontaneous defibrillation as compared with controls. The combination of the compounds improved cardiac function and resulted in 83% (P < 0.05) spontaneous defibrillation. In separate experiments, 2,5-dihydroxybenzoic acid formation in the perfusate as a marker of hydroxyl radical formation was measured by high-performance liquid chromatography and cardiac superoxide production was assessed by lucigenin-enhanced chemiluminescence during pacing-induced VF. Glibenclamide did not affect hydroxyl radical generation or myocardial superoxide content during VF. The conclusion is that glibenclamide exerts a defibrillatory action and improves post-VF cardiac function in rat hearts and these effects are independent from K(ATP) and free radicals.
authors.affiliation: Cardiovascular Research Group, Department of Biochemistry, University of Szeged, Szeged, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Csonka
authors.forename: Annamária
authors.initials: A
authors.lastname: Onody
authors.forename: Tamás
authors.initials: T
authors.lastname: Csont
authors.forename: Péter
authors.initials: P
authors.lastname: Ferdinandy
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid; D003326:Coronary Circulation / Q000187:drug effects; D019806:Cromakalim / Q000494:pharmacology; D004558:Electric Stimulation; D005905:Glyburide / Q000494:pharmacology* / Q000627:therapeutic use; D006339:Heart Rate / Q000187:drug effects; D017665:Hydroxyl Radical / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology; D014693:Ventricular Fibrillation / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D000889:Anti-Arrhythmia Agents; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D014665:Vasodilator Agents; D019806:Cromakalim; D013481:Superoxides; D017665:Hydroxyl Radical; D000255:Adenosine Triphosphate; D005905:Glyburide