Contribution of capillary endothelium to cor pulmonale development in experimental lung emphysema

The aim of this study was the ultrastructural analysis of the changes in the endothelium of myocardial capillaries and the processes observed in their vicinity in consecutive stages of experimental lung emphysema. Emphysematous changes in the lungs of Wistar rats were induced with a single intraperitoneal infusion of proteolytic enzyme solution, papain, in a dose of 20 mg/kg b.w./0.5 ml PBS. Ultrastructural analysis of the changes within the right ventricle and the subendocardial part of the left ventricle of the heart was made by a transmission electron microscope after 1, 3 and 6 months following papain administration. Special attention was paid to the analysis of changes found in the vicinity of newly formed myocardial capillaries. Animals killed after 1 and 3 months following papain infusion showed blurred borderline between the endothelium of the newly formed myocardial capillaries and perivascular connective matrix. The new vessels had poorly developed basement membrane. Fibrillary structures and/or collagen fibrils were found instead. The latter frequently demonstrated features of disorders in the structure and spatial distribution. Neither fibroblasts nor their processes were observed in the vicinity of the new collagen fibrils. Pericytes were occasionally present. In the later period (6 months from intratracheal papain infusion) well formed collagen fibres dominated in the vicinity of myocardial capillaries. The results of the ultrastructural analysis suggest the possibility of active contribution of endothelial cells to the processes of perivascular fibrosis within the myocardium in the course of experimental lung emphysema.