Downregulated cardiac annexin VI mRNA and protein levels in chronically fibrillating human atria.
OBJECTIVE
We compared the expression and distribution of atrial annexin VI between patients with atrial fibrillation (AF) or sinus rhythm (SR).


METHODS
Atrial appendages were obtained during cardiac surgery from 20 patients with chronic AF and 34 matched controls in SR. The expression and distribution of annexin VI were analyzed using semiquantitative RT-PCR, Western blotting and immunoconfocal microscopy.


RESULTS
In the AF group, compared to SR, the mRNA was reduced to <35% and the protein to <50% in amount (for each atrium, all p < 0.01). Immunoconfocal microscopy confirmed the downregulation of annexin VI protein in AF and demonstrated the colocalization of annexin VI with both Na(+)/Ca(2+) exchangers and L-type Ca(2+) channels in the sarcolemma, but not with ryanodine receptors in the sarcoplasmic reticulum.


CONCLUSIONS
Atrial annexin VI, spatially colocalized with both Na(+)/Ca(2+) exchangers and L-type Ca(2+) channels in the myocyte membrane, is downregulated during chronic AF.
Ueng
Kwo-Chang
KC
Division of Cardiology and Cardiovascular Surgery, Institute of Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan.
Lin
Chung-Sheng
CS
Yeh
Hung-I
HI
Wu
Yi-Liang
YL
Liu
Rosa Huang
RH
Tsai
Chin-Feng
CF
Tsai
Tsung-Po
TP
Chen
Shih-Ann
SA
D000199:Actins / Q000378:metabolism; D000368:Aged; D017317:Annexin A6 / Q000378:metabolism*; D001281:Atrial Fibrillation / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D016009:Chi-Square Distribution; D002908:Chronic Disease; D015897:Comorbidity; D015536:Down-Regulation; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D018709:Statistics, Nonparametric
D000199:Actins; D017317:Annexin A6; D015415:Biomarkers; D012333:RNA, Messenger