The model of functional disorders in rats with kidney nephrectomy ¾ in comparison with a high-salt diet

BACKGROUND. Modeling of chronic kidney disease using nephrectomy of 5/6 kidney parenchyma is actively used in experimental nephrology. However, the remaining 17 % of the organ parenchyma is associated with severe renal fibrosis in humans. A high-salt diet has traditionally been considered as a systemic hemodynamic model for the development of chronic kidney disease.THE AIM: to compare the functional disorders that occur in rats with nephrectomy of ¾ of the kidneys and when using only a high-salt diet.MATERIAL AND METHODS. The study was performed on 30 male Wistar rats. The animals were randomly divided into 3 equal groups: control (falsely operated, L), high-salt diet (falsely operated, LVD), nephrectomy ¾ renal parenchyma (NE). The rats received a balanced laboratory feed daily, differing only in the content of sodium chloride (NaCl). In the L and NE groups, rats received a feed containing 0.34 % NaCl, and in the VD group – 4 % NaCl. The duration of follow-up was 16 weeks. Systolic blood pressure (SBP) was measured on the tail by the cuff method. The serum and urine concentrations of creatinine, urea, potassium, sodium, chlorine, as well as the degree of proteinuria and albuminuria were determined.RESULTS. During the observation, the SBP in group L did not change. In the LVD group, SBP increased from 120 [120; 125] mmHg to 130.0 [125.0; 140.0] mmHg, p=0.011. In the NE group, SBP also increased from 120 [120; 125] mmHg to 135.0 [132.5; 137.5] mmHg, p=0.011. In the LVD group, there was an increase in serum creatinine concentration compared to the control to 52.5 [50.0; 56.0] mmol/l, p=0.0001; urea to 6.0 [5.6; 6.6] mmol/l, p=0.0001; potassium to 5.6 [5.3; 5.8] mmol/l, p=0.0001; chlorine up to 87.5 [86.6; 87.9] mmol/l, p= 0.0001. At the same time, creatinine clearance decreased from 187.5 [160.0; 205.0] ml/min in the L group to 92.0 [81.2; 99.0] ml/min, p=0.0003 in the LVD group and to 83.9 [65.7; 85.9] ml/min p=0.0001 in the NE group. The value of albuminuria before the end of the experiment was statistically significantly higher compared to the control in both the LVD group of 12.12 [6.36;18.41] mg/g creatinine, p= 0.0001, and in the NE group of 72.5 [61.6; 92.9] mg/g creatinine, p= 0.0001. When conducting a nonparametric correlation analysis (all three observation groups were combined), a statistically significant relationship was noted between the level of SBP after 1 month from the start of the experiment and the amount of albuminuria at its completion (Rs=0.583 p=0.001). A statistically significant relationship between the value of SBP and creatinine clearance was revealed before the end of the experiment (Rs=-0.700 p=0.005). Also, before the end of the experiment, a statistically significant relationship between albuminuria and creatinine clearance was revealed (Rs=-0.671 p=0.006).CONCLUSION. The NE model of the renal parenchyma is expected to be accompanied by the development of less severe functional changes compared to NE 5/6 of the renal parenchyma. In this regard, we assume that its use may be useful in studying the effectiveness of nephroprotective measures at the initial stages of CKD development. The negative effects of a high-salt diet are comparable in a number of indicators to nephrectomy of the renal parenchyma. Traditionally, an increase in salt intake is associated with an increase in blood pressure, which could result in an increase in albuminuria. However, we could not identify any relationships between albuminuria and the value of SAD. We assume that the model of a high-salt diet can be considered as a variant of a local, rather than a systemic hemodynamic model of the development of chronic kidney disease. In the future, we will present the results of nephrobiopsy in the experimental groups described above.