ULTRASTRUCTURAL CHANGES IN THE KIDNEYS OF RATS DURING THE EARLY AND LATE STAGES OF ACUTE RESPIRATORY DISTRESS SYNDROME

Introduction. Acute respiratory distress syndrome (ARDS) is characterized by severe hypoxemia and activation of the inflammatory cascade, which leads to multi-organ failure. Kidneys are one of the organs commonly affected by ARDS. However, the extent of ultrastructural changes in the parenchyma and stroma of the kidneys at different stages of ARDS progression remains unclear. The aim of this study was to use transmission electron microscopy to study the main components of the kidneys in rats at the early and late stages of experimentally induced ARDS. Materials and methods. The study included 24 healthy, sexually mature male rats weighing 200–220 g, divided into three groups: intact animals, 24 hours post-ARDS induction, and 14 days after the start of the experiment. ARDS was modeled by intranasal administration of lipopolysaccharide (5 mg/kg body weight) under anesthesia with ketamine at a dose of 50 mg/kg. Terminal anesthesia was performed using sodium thiopental at a dose of 150 mg/kg. Results: Submicroscopic examination of the kidneys from intact rats revealed no species-specific structural abnormalities. In the early stage of ARDS (24 hours post-modeling), renal corpuscles showed signs of vascular endothelial damage, fragmentation of the glomerular basement membrane, and degeneration of organelles and nuclear components in tubular epithelial cells. By day 14 of ARDS progression, signs of damage to the filtration barrier persisted, resulting in podocyte swelling. However, partial restoration of the tubular epithelial cell structure was observed, indicating the onset of the resolution phase of ARDS, as evidenced by the gradual recovery of the kidney ultrastructure. Conclusions. During the early stage of modeled ARDS, kidney damage manifests through destructive changes in the glomerular apparatus and renal tubular epithelial cells. In the late stage, although glomerular damage remains, partial restoration of the renal tubular epithelial cell structure is still evident.