[Hepatic structure remodeling after an experimental pulmonary trunk stenosis and following its operative correction]

Changes in the liver were studied in 25 puppies with experimental pulmonary trunk stenosis of 6-12 months duration and 10 animals after the elimination of this defect. Control group included 10 dogs of the corresponding age. A complex of histological, morphometric, electron microscopic and immunohistochemical methods was used. During the modeling of pulmonary trunk stenosis, the resistance of hepatic afferent vessels to hepatic blood flow was increased due to the venous-arterial and venous-venous reactions. In the arteries, the bundles of smooth myocytes (SM) of the intimal muscle were formed together with the musculo-elastic sphincters, polypoid cushions, while in the branches of the portal vein, the intimal SM bundles and the valves appeared. In the efferent veins, the muscular elevations were hypertrophied. In all the vessels the thickening of the walls was observed, and in the media of the arteries, there were signs of sclerosis and the increased expression of alpha-smooth muscle actin (alpha-SMA). Hepatocytes demonstrated marked ultrastructural changes: mitochondrial matrix swelling, partial destructions of their cristae, dilation of endoplasmic reticulum cisterns. After the elimination of the defect, previously formed vascular adaptation reactions were found to disappear, the tone of the blood vessels in the liver decreased, causing the regression of hypertrophic changes of their media. The number of the arterial blood vessels with intimal muscle, sphincters and cushions decreased. The expression of alpha-SMA in the media of the arteries was also reduced. In hepatic efferent veins, the muscular elevations became attenuated. The dystrophic changes in hepatocytes regressed at both light-microscopic and the ultrastructural level.