Vulnerability to ventricular arrhythmias [corrected] and heterogeneity of action potential duration in normal rats.
In normal rats, we analysed the arrhythmogenic role of intrinsic action potential duration (APD) heterogeneity. In each animal, ventricular arrhythmic events (VAEs) occurring spontaneously and during the exposure to an acute social challenge were telemetrically recorded. Action potentials were recorded from isolated left ventricular myocytes, at a pacing rate of 5 Hz (patch clamp: current-clamp mode). APDs were measured at -20 mV, -30 mV, -40 mV, -50 mV and -60 mV. The difference between the shortest and the longest APD was also computed, as an index of individual APD heterogeneity. Animals predisposed to stress-induced arrhythmias showed higher values of APD and APD heterogeneity as compared with the remaining rats. We concluded that, in the normal heart, a large intrinsic APD heterogeneity resulting from specific electrophysiological properties of ventricular myocytes is not in itself arrhythmogenic, but can predispose towards arrhythmia development under certain conditions, such as autonomic activation.
Stilli
Donatella
D
Dipartimento di Biologia Evolutiva e Funzionale-Sezione Fisiologia, Parco Area delle Scienze 11 A, 43100, Parma, Italy. stilli@biol.unipr.it
Berni
Roberta
R
Bocchi
Leonardo
L
Zaniboni
Massimiliano
M
Cacciani
Francesca
F
Sgoifo
Andrea
A
Musso
Ezio
E
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D025802:Electric Capacitance; D004562:Electrocardiography; D006352:Heart Ventricles / Q000166:cytology / Q000503:physiopathology; D008297:Male; D032383:Myocytes, Cardiac / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012919:Social Behavior; D013315:Stress, Psychological / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology*; D013686:Telemetry