|Budget Amount *help
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
Objective. To investigate the cell proliferation of renal tubular epithelium and interstitial cells on the progression of renal hypertrophy and hyperplasia.
Materials and Methods. Two experimental models of renal hypertrophy and hyperplasia, hypokalemic nephropathy and 11-deoxycorticosterone acetate (DOCA) -salt hypertansion, were studied. In potassium depletion, male Wistar rats were fed by a potassium free diet and were sacrificed at day 4,7,14 and 21. To induce DOCA-salf hypertension, male Wistar rats received a daily subcutaneous injection of 1 mg DOCA for 2 weeks and were offered a 0.9% NaCI drinking solution. The rats were sacrified 4 and 8 weeks after injection. A 24-hour continuous injection of BrdU (20 mg/hr/100g body weight) were performed before killing the animals.
Immunohistochemical staining was carried out on alcohol-fixed paraffin-embedded sections by the streptavidin-biotin complex method using monoclonal antibodies to BrdU and PCNA.A continuous injection of BrdU yields
to detect the S phase cells for 24 hours, while PCNA positive cells show the late G1 to S phase at sacrifice.
Results.In hypokalemic nephropathy, BrdU positive cells in renal cortical tubules were significantly increased 4 days after a potassium free diet, when hypokalemia appeared. Seven days after a potassium free diet, BrdU positive tubular epithelial cells (TECs) were fifthfold greater than those in controls. PCNA positive TECs were gradually increased in number. Twenty-one days after a potassium free diet, PCNA positive TECs were fourfold greater compared to controls. BrdU/PCNA positive cells was more than 1. BrdU positive Interstitial cells and PCNA positive cells in the inner stripe of outer medulla were significantly increased 4 days after a potassium free diet, when hypertrophy of cytoplasm appeared. Seven days after a potassium free diet, BrdU positive interstitial cells were 15 times greater compared to controls. In contrast to TECs, PCNA positive interstitial cells were greater than BrdU positive cells.
In DOCA-salt rats, hypertension appeared 4 weeks after injection. However, neither hyperplasia nor hypertrophy was observed in tubular cells and interstitial cells. BrdU positive cells and PCNA positive cells in DOCA-salt rats were not different in number from those in controls.
Conclusion. In hypokalemic nephropathy, the cell proliferation of TECs is more predominant and rapider than that of interstitial cells. However, the proliferation of TECs and interstitial cells is not different between DOCA-salt rats and controls. Less