THE RENIN-ALDOSTERONE AXIS IN 2 MODELS OF REDUCED RENAL MASS IN THE RAT

The renin-angiotensin-aldosterone system participates pates in chronic progressive renal disease. The studies presented here assessed the im portance of aldosterone in two different methods of reduced kidney mas s in the rat, i.e., the infarction model (INF; uninephrectomy plus inf arction of approximately two-thirds of the other kidney) and surgical excision or polectomy (POL; uninephrectomy plus surgical excision of b oth poles of the other kidney). Equivalent degrees of reduction in ren al mass were confirmed by the similarity of serum creatinines 3 d afte r the ablative procedure. Measurements were made thereafter at 2 and 4 wk postablation. Systolic arterial pressure was greater with INF at b oth 2 and 4 wk. Proteinuria was also greater in the INF group at bath time periods. The percentage of glomeruli with sclerosis measured at 4 wk tended to be greater in the INF group; however, this difference wa s not of statistical significance. At 2 wk, plasma renin activity and plasma aldosterone levels were lower in the POL group. The renin conce ntration 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 pl asma aldosterone, rats in the POL group had higher plasma potassium co ncentrations 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.