MORPHOLOGICAL AND MORPHOMETRIC CHANGES IN THE SMALL INTESTINAL OF RATS IN EMERGENCY ABDOMINAL SURGERY

Abstract

When determining lipid peroxidation (LPO) and antioxidant defense indicators in intact animals and in animals after laparotomy, it was found that the content of diene conjugates in operated animals increased by 10.46%, and the content of malondialdehyde – by 36.80%. A decrease in the activity of superoxide dismutase by 15.44%, catalase activity – by 12.90%, and SH-group content – by 5.66% was observed.In the group of animals with modeled acute small bowel obstruction (ASBO), activation of lipid peroxidation processes was noted, with an increase in diene conjugates and malondialdehyde (by 39.87% and 87.54%, respectively). Suppression of the antioxidant defense system was also observed, manifested by a decrease in superoxide dismutase activity by 39.19%, catalase activity – by 35.48%, and SH-group content – by 24.09%.The results of studying the bioenergetic state of the small intestine (SI) by ATP content showed that under experimental obstruction there was a significant decrease in ATP levels on the first day compared to the control group (by 57.89%, p<0.05), while in animals after laparotomy the decrease was 26.02%.When studying regional local blood circulation in the small intestinal wall of white rats with experimental intestinal obstruction, it was found that this indicator was reduced almost 1.5 times (p<0.05) compared with the corresponding indicator in rats after laparotomy, amounting to (37.50±1.12) ml/min per 100 g of tissue. This was associated with morphological and morphometric changes in the studied organ.The Ca²⁺ content in smooth muscle cells of the intestine in animals with experimental obstruction on the 3rd day of the study was (7.27±0.90) nmol/mg tissue, while in intact animals it was (9.78±0.60) nmol/mg tissue, which is 1.35 times lower (p<0.05). Such a decrease negatively affected the excitation and contraction processes of SI smooth myocytes.Based on the experimental data obtained regarding morphofunctional disorders, new patterns of the pathogenesis of functional small bowel obstruction before and after surgery have been revealed: calcium ion deficiency, energy starvation with pronounced oxidative stress, instability of local immune resistance, deficit of the microcirculatory bed, and disruption of structural organization at the subcellular, cellular, and tissue levels.