title: Ultrastructural changes in cardiac myocytes from Boxer dogs with arrhythmogenic right ventricular cardiomyopathy.
abstract: OBJECTIVE
  We sought to quantify the number and length of desmosomes, gap junctions, and adherens junctions in arrhythmogenic right ventricular cardiomyopathy (ARVC) and non-ARVC dogs, and to determine if ultrastructural changes existed.
  
  
  METHODS
  Hearts from 8 Boxer dogs afflicted with histopathologically confirmed ARVC and 6 dogs without ARVC were studied.
  
  
  METHODS
  Quantitative transmission electron microscopy (TEM) and Western blot semi-quantification of α-actinin were used to study the intercalated disc and sarcomere of the right and left ventricles.
  
  
  RESULTS
  When ARVC dogs were compared to non-ARVC dogs reductions in the number of desmosomes (P = 0.04), adherens junctions (P = 0.04) and gap junctions (P = 0.02) were found. The number of gap junctions (P = 0.04) and adherens junctions (P = 0.04) also were reduced in the left ventricle, while the number of desmosomes was not (P = 0.88). A decrease in the length of desmosomal complexes within LV samples (P = 0.04) was found. These findings suggested disruption of proteins providing attachment of the cytoskeleton to the intercalated disc. Immunoblotting did not demonstrate a quantitative reduction in the amount of α-actinin in ARVC afflicted samples. All Boxers with ARVC demonstrated the presence of electron dense material originating from the Z band and extending into the sarcomere, apparently at the expense of the cytoskeletal structure.
  
  
  CONCLUSIONS
  These results emphasize the importance of structural integrity of the intercalated disc in the pathogenesis of ARVC. In addition, observed abnormalities in sarcomeric structure suggest a novel link between ARVC and the actin-myosin contractile apparatus.
authors.affiliation: College of Veterinary Medicine, Cornell University, Department of Clinical Sciences, Section of Cardiology, Ithaca, NY 14853, USA.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Oxford
authors.forename: Charles G
authors.initials: CG
authors.lastname: Danko
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Kornreich
authors.forename: Karen
authors.initials: K
authors.lastname: Maass
authors.forename: Shari A
authors.initials: SA
authors.lastname: Hemsley
authors.forename: Dima
authors.initials: D
authors.lastname: Raskolnikov
authors.forename: Philip R
authors.initials: PR
authors.lastname: Fox
authors.forename: Mario
authors.initials: M
authors.lastname: Delmar
authors.forename: N Sydney
authors.initials: NS
authors.lastname: Moïse
mesh_terms: D022005:Adherens Junctions / Q000473:pathology; D000818:Animals; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000473:pathology / Q000662:veterinary*; D015153:Blotting, Western / Q000662:veterinary; D003896:Desmosomes / Q000473:pathology; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D017629:Gap Junctions / Q000473:pathology; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D032383:Myocytes, Cardiac / Q000648:ultrastructure*; D012518:Sarcomeres / Q000648:ultrastructure