Search

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.

An investigation of the relationship between nephrotensin and the renin angiotensin system was carred out. Nephrotensin was found in the plasma of rats with renal clip hypertension and with chemically induced kidney damage. There was no demonstrable correlation between presence of nephrotensin and plasma renin activity, and the pressor activity of nephrotensin was not altered by previous immunization of test animals with angiotensin II nor by pretreatment with angiotensin I converting enzyme inhibitor. These results indicate that nephrotensin is different from the components of the renin-angiotensin system.