The features of smooth muscle actin expression in the kidneys, ureters and bladder of the newborns exposed to chronic intrauterine, acute postnatal and mixed hypoxia

Abstract

The study aimed to determine the characteristics of smooth muscle actin expression in the kidneys, ureters and bladder of the newborns exposed to experimental chronic intrauterine, acute postnatal and mixed hypoxia. In this study an experiment was carried out on WAG rats on modeling chronic intrauterine, acute postnatal and mixed hypoxia. The material of the study was the tissue of the kidney of newborn rats. Immunohistochemical study was performed by the standard method using monoclonal antibodies against smooth muscle actin. Morphometrical investigation was conducted while studying the slides. In newborns, chronic intrauterine and mixed hypoxia result in significant reduction of mean value of the muscular fiber thickness in the muscular layer of the ureter and bladder, as well as in non-uniform expression of smooth muscle actin by the muscular layer cells of these organs. Acute postnatal hypoxia does not produce a damaging effect on the qualitative and quantitative characteristics of the muscular layer of the ureter and bladder of the newborns. In infants, acute postnatal hypoxia does not affect the mean value of the muscular fiber thickness in the arterioles and venules of the kidneys, ureters and bladder, while chronic intrauterine and mixed hypoxia result in a significant reduction of these indicators. Chronic intrauterine hypoxia and mixed hypoxia amplify severity of expression of smooth muscle actin by myofibroblasts in the kidneys, ureters and bladder, as well as by mesangiocytes, glomerular epithelial cells, and epithelial cells of renal tubules, which can lead to the further development of sclerotic changes in these organs in children at different stages of ontogenesis. The analysis of the features of smooth muscle actin expression in the urinary system organs of newborns found that chronic intrauterine and mixed hypoxia have a damaging effect on the urinary system organs of newborns while acute postnatal hypoxia has no damaging effect.