MORPHOFUNCTIONAL CHARACTERISTICS OF KIDNEYS IN RATS DRINKING LIMEWATER
Long-term consumption of drinking water with an increased concentration of vital trace elements Ca<sup>2</sup>+ and Mg<sup>2</sup>+ causes changes in osmo- and ion-regulating kidney functions. However, the mechanism of such changes is not entirely clear. The aim of the study was to evaluate the effect of water with an increased Ca<sup>2</sup>+ and Mg<sup>2</sup>+ concentration on kidney morphology in rats. Materials and Methods. Long-term experiments were carried out on 5 control groups of Wistar rats weighing 200-250 gr (n=110) and 4 experimental groups, which had been drinking water with different Ca<sup>2</sup>+ and Mg<sup>2</sup>+concentration for 6 months. In control groups, drinking water corresponded to sanitation and hygiene standards and contained 20 mg/dm<sup>3</sup> of Ca<sup>2</sup>+ and 7 mg/dm<sup>3</sup> of Mg<sup>2</sup>+; in experimental group 1, Ca<sup>2</sup>+concentration was 60 mg/dm<sup>3</sup>, and in experimental group 3 Mg<sup>2</sup>+ concentration was 35 mg/dm<sup>3</sup>, which corresponded to the hygienic standard; Ca<sup>2</sup>+ and Mg<sup>2</sup>+ concentration in groups 2 and 4 were equal to 120 mg/dm<sup>3</sup> and 70 mg/dm<sup>3</sup>, respectively, which corresponded to the upper limit of the hygienic standard. Ca<sup>2</sup>+concentration in groups 3 and 4 and Mg<sup>2</sup>+ concentration in groups 1 and 2 corresponded to sanitation and hygiene standards. On the 182<sup>nd</sup> day of observation, animals of all groups were removed from the experiment and their kidneys were taken for morphological analysis. Kidney samples were fixed in a 10% solution of neutral formalin (C<sub>3</sub>H<sub>7</sub>OH) for 4-7 days. The general morphological picture was studied on hematoxylin and eosin-stained survey samples. Results. The greatest changes in the renal glomerulus structure were observed in experimental groups 2 and 4. The authors observed a significant increase in the renal corpuscle area and a decrease in the urinary space area in comparison with the control. Red cell adherence in the glomerular capillaries could be explained by the loss of negative charge by proteoglycans of the red cells glycocalyx under the influence of Ca<sup>2</sup>+ and Mg<sup>2</sup>+ cations. In group 1 and group 2 kidney samples, the described morphological signs were minimal and did not differ significantly from the control. Conclusion. Consumption of drinking water with a high concentration of Ca<sup>2</sup>+ and Mg<sup>2</sup>+ leads to structural changes in the renal corpuscle and can cause impairments in the osmo- and ion-regulating kidney functions.