title: Role of atrial endothelial cells in the development of atrial fibrosis and fibrillation in response to pressure overload.
abstract: BACKGROUND
  Monocyte chemoattractant protein-1 (MCP-1)-mediated inflammatory mechanisms have been shown to play a crucial role in atrial fibrosis induced by pressure overload. In the present study, we investigated whether left atrial endothelial cells would quickly respond structurally and functionally to pressure overload to trigger atrial fibrosis and fibrillation.
  
  
  RESULTS
  Six-week-old male Sprague-Dawley rats underwent suprarenal abdominal aortic constriction (AAC) or a sham operation. By day 3 after surgery, macrophages were observed to infiltrate into the endocardium. The expression of MCP-1 and E-selectin in atrial endothelium and the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and ED1 in left atrial tissue were enhanced. Atrial endothelial cells were irregularly hypertrophied with the disarrangement of lines of cells by scanning electron microscopy. Various-sized gap formations appeared along the border in atrial endothelial cells, and several macrophages were located just in the endothelial gap. Along with the development of heterogeneous interstitial fibrosis, interatrial conduction time was prolonged and the inducibility of atrial fibrillation by programmed extrastimuli was increased in the AAC rats compared to the sham-operated rats.
  
  
  CONCLUSIONS
  Atrial endothelium responds rapidly to pressure overload by expressing adhesion molecules and MCP-1, which induce macrophage infiltration into the atrial tissues. These processes could be an initial step in the development of atrial remodeling for atrial fibrillation.
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kume
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan. Electronic address: teshima@oita-u.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Teshima
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Ichitaro
authors.initials: I
authors.lastname: Abe
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ikebe
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Oniki
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Saito
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Fukui
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Yufu
authors.affiliation: Department of Human Anatomy, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Miura
authors.affiliation: College of Judo Therapy and Acupuncture-Moxibustion, Oita Medical Technology School, Oita, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Naohiko
authors.initials: N
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000473:pathology*; D015153:Blotting, Western; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000473:pathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005355:Fibrosis / Q000473:pathology; D006325:Heart Atria / Q000473:pathology*; D006973:Hypertension / Q000150:complications; D007150:Immunohistochemistry; D000067268:Isolated Heart Preparation; D008297:Male; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017207:Rats, Sprague-Dawley
keywords: Atrial fibrillation; Endothelium; Fibrosis; Inflammation; Pressure overload