Effects of verapamil on reoxygenation and programmed electrical stimulation-induced ventricular arrhythmias in the isolated heart.
The antiarrhythmic effect of verapamil was tested on spontaneous ventricular arrhythmias during reoxygenation after 15 min of glucose-free hypoxia and on programmed electrical stimulation-(8 stimuli + 1 or 2 extrastimuli) induced ventricular fibrillation in isolated Langendorff perfused guinea pig hearts. Verapamil (1 mg/l) added during hypoxia and reoxygenation significantly reduced, during reoxygenation, the incidence of arrhythmias (46%, N = 13 vs. controls 87%, N = 30; P less than 0.01), of ventricular fibrillation (0%, N = 13 vs. controls 70%, N = 30; P less than 0.001) and of programmed stimulation-induced ventricular fibrillation (0%, N = 10 vs. controls 100%, N = 16). No effect was observed on programmed stimulation-induced ventricular fibrillation during hypoxia (90%, N = 10 vs. controls 100%, N = 10). Verapamil added during reoxygenation reduced the incidence of reoxygenation arrhythmias and ventricular fibrillation (47% and 29%, N = 17, P less than 0.01 and P less than 0.05 vs. controls, respectively) but it had no effect on programmed stimulation-induced ventricular fibrillation (100%, N = 10). It is likely that verapamil exerts its antiarrhythmic effect by preventing cellular calcium overload during hypoxia and reoxygenation.
Pahor
M
M
Divisione di Gerontologia, Università Cattolica del Sacro Cuore, Rome, Italy.
Bernabei
R
R
Gambassi
G
G
Carbonin
P U
PU
D000818:Animals; D000889:Anti-Arrhythmia Agents; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D003326:Coronary Circulation / Q000187:drug effects; D003402:Creatine Kinase / Q000378:metabolism; D004558:Electric Stimulation; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D010477:Perfusion; D014700:Verapamil / Q000494:pharmacology*
D000889:Anti-Arrhythmia Agents; D014700:Verapamil; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase