Ryanodine receptor-mediated Ca2+ events in atrial myocytes of patients with atrial fibrillation.
BACKGROUND
Many alterations in sarcoplasmic reticulum Ca(2+) handling proteins in atrial myocytes have been associated with atrial fibrillation (AF) in clinical patients, whereas the functional consequences of these alterations mostly remain unclear.


RESULTS
To know whether or not ryanodine receptor (RyR)-mediated intracellular Ca(2+) events in AF atrial myocytes are affected by protein alterations, we investigated spontaneous Ca(2+) sparks and Ca(2+) waves in intact and permeabilized atrial myocytes of AF patients (n(patients) = 21) and normal sinus rhythm (NSR) patients (n(patients) = 22) by laser scanning confocal microscopy. It was found that the frequency, amplitude and rise time of Ca(2+) sparks were comparable between AF and NSR groups, while full width and full duration at half maximum intensity significantly increased in the AF group. Along with these changes, the frequency of small and global Ca(2+) waves increased in AF atrial myocytes.


CONCLUSIONS
Our results clearly indicated that the spatiotemporal properties but not the frequency of Ca(2+) sparks were affected in AF atrial myocytes. In addition, the frequency of Ca(2+) waves increased. This profile of the alterations in RyR-mediated Ca(2+) events in AF atrial myocytes was different from previous studies. The underlying mechanisms, as well as possible reasons for this discrepancy, were discussed.
Liang
Xin
X
Bio-X Life Science Research Center, College of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Xie
Hong
H
Zhu
Pei-Hong
PH
Hu
Jun
J
Zhao
Qiang
Q
Wang
Chun-Sheng
CS
Yang
Cheng
C
D000328:Adult; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000378:metabolism* / Q000473:pathology; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D016022:Case-Control Studies; D002478:Cells, Cultured; D005260:Female; D006325:Heart Atria / Q000166:cytology; D006801:Humans; D008297:Male; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000378:metabolism*; D011336:Probability; D012016:Reference Values; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012680:Sensitivity and Specificity
D015220:Calcium Channels; D019837:Ryanodine Receptor Calcium Release Channel