Involvement of Ca(2+) in antiarrhythmic effect of ischemic preconditioning in isolated rat heart.
We investigated the relationship between the effects of ischemic preconditioning (IPC) and Ca(2+) preconditioning (CPC) on reperfusion-induced arrhythmias. In the control group (noPC), Langendorff-perfused rat hearts were subjected to 5-min zero-flow global ischemia (I) followed by 15-min reperfusion (I/R). In ischemic preconditioning groups (IPC), the hearts were subjected to three cycles of 3-min global ischemia and 5-min reperfusion. In the CPC group, the hearts were exposed to three cycles of 3-min perfusion of higher Ca(2+) (2.3 mmol/l Ca(2+)) followed by 5-min perfusion of normal 1.3 mmol/l Ca(2+), and the hearts were then subjected to I/R. Verapamil was administered in several hearts of the IPC group (VR+IPC). Ventricular arrhythmias upon reperfusion were less frequently seen in the IPC and CPC groups than in the noPC and VR+IPC groups. IPC and CPC could attenuate conduction delay and enhance shortening of the monophasic action potential duration during ischemia. The ventricular fibrillation threshold measured at 1-min reperfusion was significantly higher in the IPC and CPC groups than in the noPC and VR+IPC groups. Verapamil completely abolished the salutary effects of IPC. These results demonstrate that Ca(2+) plays an important role in the antiarrhythmic effect of IPC during reperfusion.
Hong
K
K
Department of Cardiovascular Medicine, Okayama University Medical School, Okayama, 700-8558 Japan.
Kusano
K F
KF
Morita
H
H
Fujimoto
Y
Y
Nakamura
K
K
Yamanari
H
H
Ohe
T
T
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D002118:Calcium / Q000008:administration & dosage* / Q000502:physiology*; D004594:Electrophysiology; D019194:Ischemic Preconditioning; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar
D002118:Calcium