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Effect of electrical field stimulation on spontaneous Ca 2+ transients in rat pulmonary vein cardiomyocytes (864.4)
Author(s) -
Henry Alasdair,
Rankin Andrew,
Rowan Edward,
Drummond Robert
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.864.4
Subject(s) - stimulation , intracellular , medicine , basal (medicine) , biophysics , chemistry , pulmonary vein , entrainment (biomusicology) , endocrinology , atrial fibrillation , biology , rhythm , biochemistry , insulin
The pulmonary veins (PVs) are widely recognised as an important source of ectopic electrical activity that can lead to atrial fibrillation. While the ectopic activity most likely originates in the cardiomyocytes that form an external sleeve around the PVs, the underlying mechanism remains to be elucidated. Recently, changes in the intracellular Ca 2+ concentration have been proposed to play a role. Studies were carried out on intact PVs isolated from the rat, using fluo‐4 to monitor intracellular Ca 2+ within individual cardiomyocytes. Under basal unstimulated conditions, spontaneous Ca 2+ transients were observed that were asynchronous in neighbouring cells. The frequency of spontaneous Ca 2+ transients increased from 0.45 ± 0.06 Hz to 0.59 ± 0.05 Hz (P<0.001) immediately following electrical field stimulation at 5 Hz. Increasing the external Ca 2+ concentration to 4.5 mM enhanced this effect, with the frequency of spontaneous Ca 2+ transients increasing from 0.45 ± 0.05 Hz under basal conditions to 0.91 ± 0.07 Hz after electrical stimulation (P<0.001). Thus, although electrical field stimulation significantly increased the frequency of the spontaneous Ca 2+ transients, their asynchronous nature would mean that they are unlikely to be capable of triggering an action potential. Other interventions that could lead to entrainment of the Ca 2+ transients are currently being investigated.