The renin-aldosterone axis in two models of reduced renal mass in the rat.

The renin-angiotensin-aldosterone system participates in chronic progressive renal disease. The studies presented here assessed the importance of aldosterone in two different methods of reduced kidney mass in the rat, i.e., the infarction model (INF; uninephrectomy plus infarction of approximately two-thirds of the other kidney) and surgical excision or polectomy (POL; uninephrectomy plus surgical excision of both poles of the other kidney). Equivalent degrees of reduction in renal mass were confirmed by the similarity of serum creatinines 3 d after the ablative procedure. Measurements were made thereafter at 2 and 4 wk postablation. Systolic arterial pressure was greater with INF at both 2 and 4 wk. Proteinuria was also greater in the INF group at both time periods. The percentage of glomeruli with sclerosis measured at 4 wk tended to be greater in the INF group; however, this difference was not of statistical significance. At 2 wk, plasma renin activity and plasma aldosterone levels were lower in the POL group. The renin concentration in the scar region of the kidneys in the INF group was higher than in the kidney of the POL group. In conjunction with the lower plasma aldosterone, rats in the POL group had higher plasma potassium concentrations at 2 wk. In summary, higher aldosterone and plasma renin levels distinguish the INF model from the POL and likely contribute to the greater proteinuria and hypertension in the INF model.