UNINEPHRECTOMY PREVENTS THE ISCHEMIA-INDUCED INCREASE IN RENIN-ACTIVITY

Contralateral uninephrectomy attenuates unilateral ischemic injury. Th e present work was performed to elucidate whether the beneficial effec t of uninephrectomy was associated with the modification of ischemia-i nduced changes in plasma or renal renin activity. A 60-min left renal artery occlusion was conducted in right nephrectomized (Nx) and sham-n ephrectomized (Sham-Nx) rats. The decline in inulin clearance 48 h aft er ischemia was significantly less in Nx rats than in Sham-Nx animals (0.50 +/- 0.10 vs. 0.052 +/- 0.029 ml/min/kidney, p < 0.05). Following ischemia, plasma renin activity (PRA) significantly increased in Sham -Nx (from 5.4 +/- 0.9 to 15.5 +/- 1.4 ng AI/ml/min, p < 0.01) but not in Nx (from 3.5 +/- 0.5 to 5.0 +/- 1.0 ng AI/ml/ min) animals. PRA and renal cortical renin content(2,200 +/- 225 vs. 1,257 +/- 187 ng AI/h/ mg protein, p < 0.05) were significantly less in Nx rats than in Sham- Nx animals 48 h after renal ischemia. The decrease in body weight was greater in Nx rats than in Sham-Nx animals. Plasma atrial natriuretic peptide (ANP) (195 +/- 30 vs. 302 +/- 40 pg/ml, p < 0.05) and renal do pamine (DA) content (3.2 +/- 0.5 vs. 13.7 +/- 1.3 ng/g tissue, p < 0.0 1)were rather lower in the Nx group when compared with the Sham-Nx gro up. No significant difference was found in the intrarenal content of n orepinephrine (NE) between two ischemic groups. These findings suggest ed that uninephrectomy prevents the ischemia-induced increase in renin activity. The prevention of the increase in renin activity in Nx rats is not be mediated through the modulation of ischemia-induced changes in sodium balance, plasma ANP level and/or intrarenal contents of NE and DA.