title: Optical mapping of V(m) and Ca(i)(2+) in a model of arrhythmias induced by local catecholamine application in patterned cell cultures.
abstract: Catecholamines are known to provoke cardiac arrhythmias, but important aspects such as localization of the arrhythmia source in multicellular tissue and exact ionic mechanisms are not well-known. In this work, a multicellular model of arrhythmias caused by local epinephrine application was developed; V (m) and Ca(i)(2+) changes at the arrhythmia source were measured using fluorescent dyes and high-resolution optical mapping. Cultured strands of neonatal rat myocytes (width approximately 0.4 mm) were produced by patterned growth. Epinephrine (1 micromol/l) was applied over an area of 0.3-0.6 mm via two micropipettes, and strands were stimulated by burst pacing. Local epinephrine application caused triggered arrhythmias with cycle lengths of 202-379 ms and duration of >10 s in 9 out of 16 preparations. Optical V(m) mapping demonstrated that in 78% of cases, the source of arrhythmia was located at the boundary of the locally perfused area. Staining with Ca(i)(2+)-sensitive dye Fluo-4 prevented arrhythmia induction in most cases (85%) likely due to Ca(2+) buffering by the dye. Optical Ca(i)(2+) mapping revealed non-propagated Ca(i)(2+) oscillations at the boundary of the locally perfused area in 45% cases. In conclusion, we developed a new model of catecholamine-dependent arrhythmias allowing mapping of V(m) and Ca(i)(2+) at the arrhythmia source with microscopic resolution. The arrhythmias typically originated from the boundary of the epinephrine-perfused area. The location of the arrhythmia source correlated with localized Ca(i)(2+) oscillations suggesting that arrhythmias were caused by Ca(i)(2+) overload at these locations.
authors.affiliation: Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: David Z
authors.initials: DZ
authors.lastname: Lan
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Pollard
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Knisley
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Fast
mesh_terms: D000814:Aniline Compounds; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D004837:Epinephrine / Q000494:pharmacology*; D005456:Fluorescent Dyes; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012815:Signal Processing, Computer-Assisted; D013566:Sympathomimetics / Q000494:pharmacology*; D014966:Xanthenes
chemical_list: D000814:Aniline Compounds; C409648:Fluo 4; D005456:Fluorescent Dyes; D013566:Sympathomimetics; D014966:Xanthenes; D002118:Calcium; D004837:Epinephrine