Comparative analysis of the effects of various detoxification solutions on the structure of the kidneys in experimental burn disease in rats

Abstract

The use of existing infusion solutions, as well as the development, scientific substantiation and implementation of the latest nephroprotective detoxification solutions, remain an urgent problem for combustiologists. The aim of this work is to compare the effects of various detoxification solutions (0.9 % NaCl solution and complex colloid-hyperosmolar solutions – lactoprotein with sorbitol and the newly developed HAES-LX-5 % solution) on the kidney structure in experimental burn disease in rats. The experimental rats were divided into seven groups (fifteen animals each): the first group was intact rats; the second, third and fourth groups were rats without reproduction of experimental burn disease, which had a separate intravenous infusion of 0.9 % NaCl solution, lactoprotein with sorbitol and HAES-LX-5 % at a dose of 10 ml/kg; the fifth, sixth and seventh groups were rats with experimental burn disease (by causing burn injury of the skin with an area of 21-23 % of the body surface), which under the same scheme had an intravenous infusion of the investigated solutions. All studies and the removal of rats from the experiment were performed under deep thiopental intraperitoneal anesthesia. Histological preparations of the renal cortex of the rat were stained with hematoxylin-eosin and examined on an Olympus BX51 microscope. Using ultramicrotome LKB-3 (Sweden) obtained semi-thin sections which were stained with toluidine blue and methylene blue – Azur II; and ultrathin sections were counterstained with uranyl acetate and lead citrate according to Reynolds and examined using a PEM-125K electron microscope. Morphometric measurements (estimation of the area of the vascular glomeruli, the area of the urinary lumen of the capsule of the renal corpuscles; the area of the renal tubules of the nephrons and the area of their lumens, the area of the renal corpuscles, the area of cytoplasm and nuclei of epithelial cells of tubules, and also their nuclear-cytoplasmic ratio) was carried out using the VideoTest-5.0, KAARA Image Base and Microsoft Excel on a personal computer. Statistical analysis of the obtained quantitative indicators was performed using the ІВМ SPSS v. 22.0. for Windows. Functionally different cells of nephrons have been found to die by necrosis, apoptosis and anoikis when infused with detoxification solutions during the development of burn disease; in epithelial cells of nephron tubules, mitophagy and mitoptosis occur. Mitoptosis in epithelial cells of rat tubules of nephrons with experimental burn skin injury is carried out in two ways related to: 1) destruction of the outer mitochondrial membrane; 2) preservation of the outer mitochondrial membrane and involvement of autophagic (mitophagic) mechanisms to release the cell from degraded mitochondrial material. In the first case, the mitochondria first condense, after which its matrix swells and the fragmentation of the cristae occurs due to the destruction of the junction of the cristae. Finally, the outer mitochondrial membrane breaks and the remnants of the cristae (in the form of vesicles) go into the cytoplasm. In the second case, the mitochondria condense, vesicular fragmentation of the cristae occurs, but the rupture of the outer mitochondrial membrane does not occur and the mitochondria are absorbed by the autophagosome (or transformed into the autophagosome). Next is the merger of autophagosomes with lysosomes and the formation of autophagolysosomes, which, under the conditions of effective digestion of the contents, are transformed into vacuoles. The latter are emptied by exocytosis and ensure the release of cells from degraded material. Only lactoprotein with sorbitol has a membrane-plastic effect on the strengthening (enhancement of structuring) of the mitochondrial membrane in part of the mitochondria of epithelial cells of nephron tubules, which is ultrastructurally manifested by an increase in the electron density and thickness of all components of the mitochondria. The maximum membrane effect of lactoprotein with sorbitol against mitochondria manifests itself fourteen days after the experimental burn skin injury and gradually (after twenty-one and thirty days) disappears, which is correlated with an improvement in the overall clinical condition and an improvement in the structural changes in the kidney of animals with burn disease. There is every reason to believe that increased structuration of mitochondria is a preventer of the spread of mitoptosis and mitophagy, the excess of which can lead to cell death.