Characterisation of re-entrant circuit (or rotational activity) in vitro using the HL1-6 myocyte cell line.
Fibrillation is the most common arrhythmia observed in clinical practice. Understanding of the mechanisms underlying its initiation and maintenance remains incomplete. Functional re-entries are potential drivers of the arrhythmia. Two main concepts are still debated, the "leading circle" and the "spiral wave or rotor" theories. The homogeneous subclone of the HL1 atrial-derived cardiomyocyte cell line, HL1-6, spontaneously exhibits re-entry on a microscopic scale due to its slow conduction velocity and the presence of triggers, making it possible to examine re-entry at the cellular level. We therefore investigated the re-entry cores in cell monolayers through the use of fluorescence optical mapping at high spatiotemporal resolution in order to obtain insights into the mechanisms of re-entry. Re-entries in HL1-6 myocytes required at least two triggers and a minimum colony area to initiate (3.5 to 6.4 mm2). After electrical activity was completely stopped and re-started by varying the extracellular K+ concentration, re-entries never returned to the same location while 35% of triggers re-appeared at the same position. A conduction delay algorithm also allows visualisation of the core of the re-entries. This work has revealed that the core of re-entries is conduction blocks constituted by lines and/or groups of cells rather than the round area assumed by the other concepts of functional re-entry. This highlights the importance of experimentation at the microscopic level in the study of re-entry mechanisms.
['Houston|Charles|C|', 'Tzortzis|Konstantinos N|KN|', 'Roney|Caroline|C|', 'Saglietto|Andrea|A|', 'Pitcher|David S|DS|', 'Cantwell|Chris D|CD|', 'Chowdhury|Rasheda A|RA|', 'Ng|Fu Siong|FS|', 'Peters|Nicholas S|NS|', 'Dupont|Emmanuel|E|']
D000818:Animals D001281:Atrial Fibrillation D002460:Cell Line D006325:Heart Atria D006801:Humans D008955:Models, Cardiovascular D032383:Myocytes, Cardiac D011784:Quail
Rotational activity HL1-6 myocytes Re-entry Triggers Optical mapping Monolayer culture