Uninephrectomy prevents the ischemia-induced increase in renin activity

Contralateral uninephrectomy attenuates unilateral ischemic injury. The present work was performed to elucidate whether the beneficial effect of uninephrectomy was associated with the modification of ischemia-induced changes in plasma or renal renin activity. A 60-min left renal artery occlusion was conducted in right nephrectomized (Nx) and sham-nephrectomized (Sham-Nx) rats. The decline in inulin clearance 48 h after 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 dopamine (DA) content (3.2 +/- 0.5 vs. 13.7 +/- 1.3 ng/g tissue, p < 0.01) were rather lower in the Nx group when compared with the Sham-Nx group. No significant difference was found in the intrarenal content of norepinephrine (NE) between two ischemic groups. These findings suggested 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.