The renin-angiotensin system in rats with hereditary hydronephrosis

The renin-angotensin system was studied in rats suffering from hereditary hydronephrosis in which normal blood pressure, hyperkalemia, and damage to the renal medulla and distal tubules were found. An increased serum creatinine level, decreased creatinine clearance and increased 24 hrs urine volume were observed in rats with bilateral hydronephrosis. When compared to rats with normal kidneys, bilaterally hydronephrotic animals exhibited elevated plasma renin activity (9.9 +/- 1.3/S.E./ng AI/ml/hr vs. 2.4 +/- 0.4 in rats with normal kidneys), and decreased renal renin concentration (78 +/- 4 mug AII/g vs. 132 +/- 5). No correlation between the extent of kidney damage and renal renic concentration was found. After the hyperkalemia of the hydronephrotic rats was corrected, there were significant increases in both plasma renin activity and renal renin concentration, but the renal renin concentration remained significantly lower than that observed in animals with normal kidneys. The results suggest that renin production and/or storage capacity are diminished in hydronephrotic kidneys.