title: Do calcium waves propagate between cells and synchronize alternating calcium release in rat ventricular myocytes?
abstract: The aim was to investigate the propagation of Ca(2+) waves between cells and determine whether this synchronizes alternating Ca(2+) release between cells. Experiments were carried out on electrically coupled cell pairs; spontaneous Ca(2+) waves were produced by elevating external Ca(2+). There was a significant difference in the ability of these waves to propagate between cells depending on the orientation of the pairs. Although almost all pairs connected by side-to-side contacts showed propagating Ca(2+) release, this was very uncommon in end-to-end cell pairs. Confocal studies showed that there was a gap at the intercalated disc consisting of cell membranes and a region of cytoplasm devoid of sarcoplasmic reticulum. This gap was 2.3 μm in length and is suggested to interfere with Ca(2+) wave propagation. The gap measured was much smaller between side-to-side contacts: 1.5 μm and so much less likely to interfere with propagation. Subsequent experiments investigated the synchronization between cells of Ca(2+) alternans produced by small depolarizing pulses. Although this alternation results from beat-to-beat alternation of intracellular Ca(2+) wave propagation, there was no evidence that propagation of Ca(2+) waves between cells contributed to synchronization of this alternans.
authors.affiliation: Unit of Cardiac Physiology, Core Technology Facility, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: D A
authors.initials: DA
authors.lastname: Eisner
authors.forename: S C
authors.initials: SC
authors.lastname: O'Neill
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002450:Cell Communication; D002462:Cell Membrane / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism*; D007365:Intercellular Junctions / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013997:Time Factors