Alteration of gap junctions and connexins in the right atrial appendage during cardiopulmonary bypass.
OBJECTIVE
We investigated the influence of cardiopulmonary bypass on cardiomyocyte gap junctions and connexins.


METHODS
Samples were collected at intervals during operation from the right atrial appendage in 21 patients (mean [+/- SD] age 55 +/- 21 years). Immunodetection of connexins was conducted by Western blotting and confocal microscopy with parallel electron microscopic examination of gap junctions.


RESULTS
Downregulation of connexin 43 during the course of operation occurred in more than half of the patients. The mean densitometric value of connexin 43 decreased by 23%, with samples from patients with coronary artery disease showing a greater reduction than seen in those from patients with other diseases (31% +/- 22% vs 10% +/- 24%, P =.04). Such alterations were confirmed by confocal microscopy, which also demonstrated reduced connexin 45 immunolabeling in most patients. Electron microscopy revealed a reduction in the dimensions of cell membrane-located gap junctions and more frequent intracytoplasmic gap junctional membrane in samples from later time points (P =.04).


CONCLUSIONS
Downregulation of connexins accompanied by a reduction in gap junctions is common in the cardiomyocytes of the right atrial appendage during cardiopulmonary bypass. The association of a marked reduction in connexin 43 with coronary artery disease may imply inadequate intraoperative cardiac protection in patients with this disease.
Yeh
Hung-I
HI
Departments of Cardiac Medicine and Medical Research, Mackay Memorial Hospital, Taipei Medical University, Taipei, Taiwan.
Hou
Shou-Hsien
SH
Hu
Hsiang-Rui
HR
Lee
Yi-Nan
YN
Li
Jiun-Yi
JY
Dupont
Emmanuel
E
Coppen
Steven R
SR
Ko
Yu-Shien
YS
Severs
Nicholas J
NJ
Tsai
Cheng-Ho
CH
D020517:Atrial Appendage / Q000378:metabolism*; D015153:Blotting, Western; D002315:Cardiopulmonary Bypass; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D017629:Gap Junctions / Q000378:metabolism*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008875:Middle Aged; D000097003:Gap Junction alpha-5 Protein
D018031:Connexin 43; D017630:Connexins; D000097003:Gap Junction alpha-5 Protein