Mechanisms of the early and late response of the kidney to contralateral nephrectomy.

The immediate (1 day, D1) and late (90 days, D90) effects of unilateral nephrectomy on contralateral renal hemodynamics, and the renal handling of electrolytes and water were investigated in the whole animal. The immediate and late ability of the remnant kidney to autoregulate perfusate flow and glomerular filtration rate (GFR) was studied in the isolated perfused kidney of the rat. In the whole animal, in D1 rats as compared to controls, GFR calculated for a single kidney increased from 0.85 +/- 0.3 to 1.1 +/- 0.2 ml/min (p less than 0.05). In D90 rats GFR increased further and was similar to prenephrectomy GFR (1.4 +/- 0.5 vs. 1.7 +/- 0.5 ml/min, p NS). Urinary prostanoid excretion in 24 h, calculated for one kidney, increased by 50-500% in D1 rats, but returned to prenephrectomy values in D90 rats. In the isolated perfused kidney, decreasing perfusion pressure (PP) from 100 to 70 mmHg did not change the renal vascular resistance (RVR) in control and D90 kidneys, but in D1 kidneys RVR decreased from 8.6 +/- 1.3 to 7 +/- 1.3 mm Hg/ml/min (p less than 0.05). In D90 kidneys RVR was significantly lower as compared to control and D1 kidneys at all perfusion pressures. Decreasing PP from 100 to 70 mm Hg resulted in a significant decrease in perfusion flow in control, D1 and D90 kidneys, while with the increase in PP from 100 to 130 mm Hg the perfusion flow increased significantly in all three kidney groups.(ABSTRACT TRUNCATED AT 250 WORDS)