Pulmonary venous structural remodeling in a canine model of chronic atrial dilation due to mitral regurgitation.
OBJECTIVE
Structural remodelling plays an important role in the genesis and maintenance of atrial fibrillation (AF). Although some studies that associate structural remodelling with atrial dilation have been reported, structural pulmonary venous (PV) remodelling due to chronic atrial dilation remains unclear.


METHODS
Six sham dogs and five mitral regurgitation (MR) dogs (three months after partial mitral valve avulsion) were studied. Separate cryosections from the PV and left atrium (LA) were immunolabelled with antibodies against connexin (Cx) 40 and Cx43 and analyzed by confocal laser scanning microscopy. Tissue samples from the PV and LA were stained with hematoxylin and eosin, and Masson's trichrome.


RESULTS
In MR models, a decrease in Cx40 (0.57+/-0.2% versus 1.18+/-0.3%, P<0.05) and Cx43 (0.48+/-0.2% versus 1.56+/-0.5%, P<0.05) expression was observed compared with sham dogs. The distribution pattern of Cx40 and Cx43 changed from homogeneous to heterogeneous. Gap junction remodelling was not observed in the LA. In Masson's trichrome-stained sections from MR dogs, regions with increased interstitial fibrosis were present in the PV. Thickness in the PV and the PV-LA junction did not change in the MR group.


CONCLUSIONS
The present study demonstrated a decrease in Cx40 and Cx43 expression and increased interstitial fibrosis in PV due to MR. These changes may potentially be a mechanism that renders the dilated atria more susceptible to AF.
Sun
Qi
Q
Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China.
Tang
Min
M
Pu
Jielin
J
Zhang
Shu
S
D000818:Animals; D001281:Atrial Fibrillation / Q000473:pathology*; D018880:Atrial Premature Complexes / Q000473:pathology; D006332:Cardiomegaly / Q000473:pathology; D002908:Chronic Disease; D018031:Connexin 43 / Q000032:analysis; D017630:Connexins / Q000032:analysis; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D005355:Fibrosis / Q000473:pathology; D017629:Gap Junctions / Q000473:pathology; D006325:Heart Atria / Q000473:pathology; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008944:Mitral Valve Insufficiency / Q000473:pathology*; D011667:Pulmonary Veins / Q000473:pathology*; D013318:Stroke Volume / Q000502:physiology; D000097003:Gap Junction alpha-5 Protein
D018031:Connexin 43; D017630:Connexins; D000097003:Gap Junction alpha-5 Protein