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This Article Full Text Full Text (PDF) All Versions of this Article: 295/4/H1460    most recent 00414.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Etzion, Y. Articles by Katz, A. Search for Related Content PubMed PubMed Citation Articles by Etzion, Y. Articles by Katz, A.

New insights into the atrial electrophysiology of rodents using a novel modality: the miniature-bipolar hook electrode

¹Cardiac Arrhythmia Research Laboratory and ²Internal Medicine Division, Soroka University Medical Center; and ³Department of Physiology, Faculty of Health Science and ⁴Cardiology Department Barzilai Medical Center, Ashkelon Campus, Ben-Gurion University of the Negev, Beer-Sheva, Israel

Submitted 19 April 2008 ; accepted in final form 24 July 2008

Studies of atrial electrophysiology (EP) in rodents are challenging, and available data are sparse. Herein, we utilized a novel type of bipolar electrode to evaluate the atrial EP of rodents through small lateral thoracotomy. In anesthetized rats and mice, we attached two bipolar electrodes to the right atrium and a third to the right ventricle. This standard setup enabled high-resolution EP studies. Moreover, a permanent implantation procedure enabled EP studies in conscious freely moving rats. Atrial EP was evaluated in anesthetized rats, anesthetized mice (ICR and C57BL6 strains), and conscious rats. Signal resolution enabled atrial effective refractory period (AERP) measurements and first time evaluation of the failed 1:1 atrial capture, which was unexpectedly longer than the AERP recorded at near normal cycle length by 27.2 ± 2.3% in rats (P < 0.0001; n = 35), 31.7 ± 8.3% in ICR mice (P = 0.0001; n = 13), and 57.7 ± 13.7% in C57BL6 mice (P = 0.015; n = 4). While AERP rate adaptation was noted when 10 S1s at near normal basic cycle lengths were followed by S2 at varying basic cycle length and S3 for AERP evaluation, such rate adaptation was absent using conventional S1S2 protocols. Atrial tachypacing in rats shortened the AERP values on a timescale of hours, but a reverse remodeling phase was noted thereafter. Comparison of left vs. right atrial pacing in rats was also feasible with the current technique, resulting in similar AERP values recorded in the low right atrium. In conclusion, our findings indicate that in vivo rate adaptation of the rodent atria is different than expected based on previous ex vivo recordings. In addition, atrial electrical remodeling of rats shows unique remodeling-reverse remodeling characteristics that are described here for the first time. Further understanding of these properties should help to determine the clinical relevance as well as limitations of atrial arrhythmia models in rodents.

atrial effective refractory period; rate adaptation; electrical remodeling

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