title: Of rodents and humans: a light microscopic and ultrastructural study on cardiomyocytes in pulmonary veins.
abstract: Cardiomyocytes in pulmonary veins (PVs) have been reported in rodents and humans. In humans they were related to atrial arrhythmias, including atrial fibrillation (AF). To investigate histological similarities and differences in PV cardiomyocyte localization and distribution, we performed comparative light and electron microscopic studies on humans, rats and mice, and generated a transgenic mouse strain. Results on mice (C57BL/6 and BALBc) and rats (Wistar) revealed that cardiomyocytes regularly extend from the hilus along venous vessels into the lung tissue surrounding individual intrapulmonary veins of varying diameters (70-250 microm). The cardiomyocytes showed the ultrastructure of a normal working myocardium with intact intercalated discs and tightly packed contractile filaments. In both lung and hilus cardiomyocytes were localized either close to the basal lamina of the endothelium or separated from it by smooth muscle cells and/or collagen fibres. In humans (autopsies, n=20) extrapericardiac cardiomyocytes were only found in 23 out of 78 veins and showed an incomplete sleeve at the lung hilus. In addition, cardiomyocytes occurred significantly more often in right than in left veins, however, never in intrapulmonary veins. We discuss the hypothesis that the variance in distribution of PV cardiomyocytes in humans and rodents might reflect the difference in pathogenesis and development of AF.
authors.affiliation: Institute of Pathology, Ludwig-Maximillians-University Munich, Germany. elisabeth.deindl@med.uni-muenchen.de
authors.forename: Josef
authors.initials: J
authors.lastname: Mueller-Hoecker
authors.forename: Frigga
authors.initials: F
authors.lastname: Beitinger
authors.forename: Borja
authors.initials: B
authors.lastname: Fernandez
authors.forename: Olaf
authors.initials: O
authors.lastname: Bahlmann
authors.forename: Gerald
authors.initials: G
authors.lastname: Assmann
authors.forename: Christian
authors.initials: C
authors.lastname: Troidl
authors.forename: Ilias
authors.initials: I
authors.lastname: Dimomeletis
authors.forename: Stefan
authors.initials: S
authors.lastname: Kääb
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Deindl
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation; D003001:Cloning, Molecular; D006801:Humans; D008168:Lung / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology / Q000648:ultrastructure*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000648:ultrastructure*; D011667:Pulmonary Veins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar