Katarzyna Michalek

Immunohistochemical identification of aquaporin 2 in the kidneys of young beef cattle

Abstract Aquaporin 2 (AQP2) is a small, integral tetrameric plasma membrane protein that is expressed in mammalian kidneys. The specific constitution of this protein and its selective permeability to water means that AQP2 plays an important role in hypertonic urine production. Immunolocalization of AQP2 has been studied in humans, monkeys, sheep, dogs, rabbits, rats, mice and adult cattle. We analyzed the expression of AQP2 in kidneys of 7-month-old Polish-Friesian var. black and white male calves. AQP2 was localized in the principal cells of collecting ducts in medullary rays penetrating the renal cortex and in the collecting ducts of renal medulla. AQP2 was expressed most strongly in the apical plasma membrane, but expression was observed also in the intracellular vesicles and basolateral plasma membrane. Our study provides new information concerning the immunolocalization of AQP2 in calf kidneys.

Renal regulation of sodium, potassium and chloride balance in single- and twin-pregnant goats.

The aim of these studies was to analyse and compare changes in selected parameters of renal function in terms of water-electrolyte balance regulation in single- and twin-pregnant goats. Clearance analyses were carried out on 16 pregnant White Improved goats (8 in single and 8 in twin gestation). Blood plasma and urine samples were analysed for the concentration of inulin, endogenous creatinine, sodium, potassium, and chlorides. It has been demonstrated that glomerular filtration rate (GFR) in the goat kidney does not change significantly during gestation. GFR recorded from the 1st week until the 20th week of gestation in twin-pregnant goats was only slightly higher compared to those observed in single-pregnant does. Blood plasma concentrations of major electrolytes, i.e. sodium, potassium and chloride ions, did not differ significantly in pregnant and non-pregnant goats, and remained within the reference values. From the very beginning of gestation, the single-pregnant goats showed increased renal potassium clearance; however, the level of sodium clearance remained stable. On the other hand, sodium clearance increased from the 2nd month of gestation in the twin-pregnant goats, while the load of excreted potassium did not change. These changes had probably resulted from varied levels of aldosterone and progesterone and their mutual proportions differing between the groups.

Effects of an immunosuppressive treatment on the rat prostate

The aim of this study was to determine the influence of different combinations of immunosuppressive drugs on the morphology, ultrastructure, and expression of proliferating cell nuclear antigen and cytoskeleton proteins in the rat dorsolateral prostate. The studies were conducted on 48 male Wistar rats. The animals were divided into eight groups: a control group and seven experimental groups. For 6 months, the animals in the experimental groups were administered a combination of drugs including rapamycin (Rapa), cyclosporin A, tacrolimus (Tac), mycophenolate mofetil, and prednisone (Pred), according to the standard three-drug regimens for immunosuppressive therapy used in clinical practice. An evaluation of the morphology and ultrastructure was conducted, and a quantitative evaluation of the expression of proliferating cell nuclear antigen and desmin- and cytokeratin-positive cells with weak, moderate, and strong expression was performed. The combination of Rapa, Tac, and Pred caused the smallest morphological and ultrastructural changes in the rat prostate cells. In the case of rats whose treatment was switched to Rapa monotherapy, a decreased percentage of proliferating cells of both the glandular epithelium and the stroma was found. Decreases in body weight and changes in the expression of cytokeratin and desmin were observed in all the experimental rats. The combination of Rapa, Tac, and Pred would seem to be the most beneficial for patients who do not suffer from prostate diseases. Our results justify the use of inhibitors of the mammalian target of Rapa in the treatment of patients with prostate cancer. The changes in the expression of cytoskeleton proteins may be the result of direct adverse effects of the immunosuppressive drugs, which are studied in this article, on the structure and organization of intermediate filament proteins.