THE COMBINED INFLUENCE OF AGE AND REDUCE THE WEIGHT OF EXISTING NEPHRONS ON MYOCARDIAL REMODELING IN RATS

THE AIM: to evaluate myocardial remodeling features in Wistar rats after long time (4 month) of experimental nephrectomy (4 month of rat life is about 10-12 years of human life). MATERIAL AND METHODS. Male Wistar rats after 5/6 nephrectomy were studied (NE; n=9). Sham operated rats (SO; n=8) used as control (C). Animals were taken out of the experiment four month after NE or sham operation. Blood pressure (BP, mm Hg) was measured, serum concentrations of creatinine (Cr, mmol/l), urea (Ur, mmol/l), total calcium (Ca, mmol/l), inorganic phosphorous (Pi, mmol/l) and triglycerides (Tg, mmol/l) were determined. Left ventricular mass index (LVMI) was calculated as the ratio: ventricular mass/body mass (mg/g). Morphological changes of the myocardium were evaluated by quantitative morphometry using the system VideoTest 5.2 In each preparation measurements were carried out in several fields of view. The number of measurements of each parameter is indicated as N. Results are presented as mean±SE. Unpaired Student t-test was used. RESULTS. In NE group Cr (0.072±0.009), Ur (17.8±2.0), Tg (2.04±0.07), BP (165.0±5.0), LVMI (2.72± 0.11) were significantly higher than in control group (0.030±0.004), p<0.01; 5.4± 0,8), p<0.001; 0.52±0.05, p<0.001; 130.0±5.0, p<0.01; 2.35±0.09, p<0.01, respectively). Ca in NE was significantly lower, than in SO rats (2.07±0.09 vs 2.35±0.09, respectively; p<0.01) and Pi - significantly higher (2.62±0.010 vs 2.05±0.05; p<0.01, respectively). Thickness of cardiomyocytes (14.19±0.08, μm, N=1433), area of the nucleus of cardiomyocytes (30.1±0.65, μ^ι², N=359) and area of fibrosis (6231±113.8, μm², N=359) in NE rats were significantly higher than in control group (11.77±0.08, μ^ι, N=1520); (28.06±0.58, μm², N=300); (2773±45.9, μm², N=300), respectively, p<0.001 in all cases. CONCLUSION. 4 months after kidney tissue mass reduction in rats revealed severe myocardial remodeling expressed both hypertrophy and fibrosis. However, the exact contribution of uremia and age in myocardial remodeling needs further investigation.

cardio-vascular system, age, myocardial hypertrophy, cardiomyocytes, experimental renal failure

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