Single and multiple early afterdepolarization caused by nickel in rat atrial muscle.
We examined the possible role of the Na-Ca exchange (NCX) in the arrhythmogenesis in rat atrial preparations applying microelectrode technique. In control Tyrode solution preparations isolated from the sinoatrial area contracted with frequency of 48+/-4 min(-1) (group I) or 84+/-7 min(-1) (group II). In preparation beating with low frequency partial inhibition of NCX by administration of Ni2+ (0.3 mmol/l) to the bath solution caused single early afterdepolarization (EAD) on the 15th min. During the following five minutes they were transformed into multiple EADs from 4 to 47 (action potentials) with general duration of 1-12 s. The effects were reversible. Ni2+ (0.3 mmol/l) in the preparations beating with higher rate (group II) did not cause multiple EADs, but after higher Ni2+ concentration (0.5 mmol/l) single EAD was observed more often. It was concluded that Ca2+ overload due to partial block of the NCX can contribute to the development of atrial tachyarrhythmias.
Golovko
V A
VA
Institute of Physiology Komi Science Centre Ural Division RAS, Syktyvkar, Russia. golovko@physiol.komisc.ru
Bojtsov
I V
IV
Kotov
L N
LN
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D016275:Atrial Function / Q000187:drug effects* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006329:Heart Conduction System / Q000187:drug effects* / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D009532:Nickel / Q000494:pharmacology*; D051381:Rats
D009532:Nickel