title: Structural remodelling of cardiomyocytes in the border zone of infarcted rabbit heart.
abstract: Cardiomyocyte dedifferentiation, as detected in hibernating myocardium of chronic ischemic patients, is one of the characteristics seen at the border of myocardial infarcts in small and large animals. Our objectives were to study in detail the morphological changes occurring at the border zone of a rabbit myocardial infarction and its use as model for hibernating myocardium. Ligation of the left coronary artery (LAD) was performed on rabbit hearts and animals were sacrificed at 2, 4, 8 and 12 weeks post-infarction. These hearts together with a non-infarcted control heart were perfusion-fixed and tissue samples were embedded in epoxy resin. Hibernating cardiomyocytes were mainly distributed in the non-infarcted region adjacent to the border zone of infarcted myocardium but only in a limited number. In the border zone itself vacuolated cardiomyocytes surrounded by fibrotic tissue were frequently observed. Ultrastructural analysis of these vacuolated cells revealed the presence of a basal lamina inside the vacuoles adjacent to the surrounding membrane, the presence of pinocytotic vesicles and an association with cisternae of the sarcoplasmatic reticulum. Myocyte quantitative analyses revealed a gradual increase in vacuolar area/total cell area ratio and in collagen fibril deposition inside the vacuoles from 2 to 12 weeks post-infarction. Related to the remote zone, the increase in cell width of myocytes located in and adjacent to the border zone demonstrated cellular hypertrophy. These results indicate the occurrence of cardiomyocyte remodelling mechanisms in the border zone and adjacent regions of infarcted myocardium. It is suggested that the vacuoles represent plasma membrane invaginations and/or dilatations of T-tubular structures.
authors: Department of Molecular Cell Biology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, P.O. Box 616, 6200 MD, Maastricht, The Netherlands. r.driesen@molcelb.unimaas.nl
authors: Ronald B
authors: RB
authors: Driesen
authors: Fons K
authors: FK
authors: Verheyen
authors: Petra
authors: P
authors: Dijkstra
authors: Fred
authors: F
authors: Thoné
authors: Jack P
authors: JP
authors: Cleutjens
authors: Marie-Hélène
authors: MH
authors: Lenders
authors: Frans C S
authors: FC
authors: Ramaekers
authors: Marcel
authors: M
authors: Borgers
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000473:pathology; D009203:Myocardial Infarction / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000473:pathology* / Q000648:ultrastructure; D011817:Rabbits; D014617:Vacuoles / Q000648:ultrastructure; D020257:Ventricular Remodeling / Q000502:physiology*
chemical_list: D003094:Collagen