title: In situ visualization of the intracellular Ca2+ dynamics at the border of the acute myocardial infarct.
abstract: Ischemic insult to the heart produces myocyte Ca2+ ([Ca2+]i) overload. However, little is known about spatiotemporal changes in [Ca2+]i within the ischemic heart in situ at the cellular level. Using real-time confocal microscopy, we successfully visualized [Ca2+]i dynamics at the border zone on the subepicardial myocardium of the heart 2 h after coronary ligations followed by loading with fluo 3/AM. Three distinct regions were identified in the acute infarcted heart. In intact regions, the myocytes showed spatially uniform Ca2+ transients synchronously to QRS complex in the electrocardiogram. The myocytes at the infarcted regions showed no fluorescence intensity (FI). At the border zones between the intact and infarcted regions, Ca2+ waves emerged sporadically and randomly, instead of Ca2+ transients, at a mean frequency of 11.5 +/- 8.5 min/cell with a propagation velocity of 151.0 +/- 35.7 microm/sec along the longitudinal axis of the individual myocytes. In addition, some myocytes within the border zone exhibited homogeneously high static FI, indicating severe Ca2+ overload. In summary, we provided the first direct evidence of abnormal [Ca2+]i dynamics in acute infarcted hearts at the cellular level. The observed diversity in spatiotemporal [Ca2+]i dynamics at the border zone may contribute to the arrhythmias or contractile failure in acute myocardial infarction.
authors.affiliation: Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tsujii
authors.forename: Hideo
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masahito
authors.initials: M
authors.lastname: Oyamada
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Fujita
authors.forename: Tetsu
authors.initials: T
authors.lastname: Hamamoto
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Takamatsu
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004562:Electrocardiography; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000378:metabolism*; D017202:Myocardial Ischemia; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D002118:Calcium