Premium
Do calcium waves propagate between cells and synchronize alternating calcium release in rat ventricular myocytes?
Author(s) -
Li Y.,
Eisner D. A.,
O’Neill S. C.
Publication year - 2012
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2012.245241
Subject(s) - beat (acoustics) , depolarization , biophysics , calcium , gap junction , endoplasmic reticulum , myocyte , wave propagation , physics , intracellular , chemistry , optics , biology , microbiology and biotechnology , biochemistry , organic chemistry
Key points• In cell pairs isolated from rat ventricular muscle, spontaneous waves of Ca 2+ ‐induced Ca 2+ release are much more likely to propagate between cells connected side to side than end to end. • Investigation of this difference using fluorescence techniques shows that the end‐to‐end connection probably contains the intercalated disc. It is this structure that accounts for the greater distance between sarcoplasmic reticulum Ca 2+ release units being so large (about 2.3 μm). At side‐to‐side connections, this distance is much less (about 1.6 μm). This variation may be the cause of the difference in propagation properties. • In cell pairs isolated from rat ventricular muscle, we have been able to induce systolic Ca 2+ alternans in‐phase between the cells in a pair. This is not due to propagation of Ca 2+ waves between cells. In some cases, wave propagation can interfere with synchrony.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 μ m 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 μ m 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.