Premium
Variability in frequency and characteristics of Ca 2+ sparks at different release sites in rat ventricular myocytes
Author(s) -
Parker Ian,
Wier Withrow
Publication year - 1997
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 - 10.1111/j.1469-7793.1997.337bb.x
Subject(s) - bursting , biophysics , calcium , chemistry , amplitude , fluorescence , transient (computer programming) , physics , biology , neuroscience , optics , organic chemistry , computer science , operating system
1 High spatial resolution confocal imaging was used to investigate spontaneous calcium release events (Ca 2+ sparks) in isolated rat cardiac myocytes loaded with the fluorescent calcium indicator fluo‐3. 2 Frequencies of sparks at different release sites varied widely, with a few sites showing sustained activities as great as 50 times the average. Sites with frequent sparks showed more rapid recovery of activity following Ca 2+ waves and locally elevated basal [Ca 2+ ]. 3 In addition to transient sparks, some sites showed bursts of rapid flurries of spark‐like events, or apparently sustained Ca 2+ liberation. Bursts remained localized to individual Z‐lines, but adjacent sites on the same Z‐line could be ‘driven’ by a bursting site to generate similar activity. 4 Individual sites showed long‐term (tens of seconds) changes in ‘modes’ of activity, with abrupt transitions in frequencies of sparking, and between transient sparks and sustained bursts. These transitions were not associated with changes in the amplitude of the sparks. 5 We conclude that spontaneous sparks are not stereotyped events generated with uniform probability at all sites. Instead, the Ca 2+ release event is variable, and some sites have a high probability of spark generation. Both factors show long‐term changes at individual sites, raising the possibility that properties of fundamental Ca 2+ release units may be subject to modulation.