1. The influence of dietary sodium intake on the glomerular filtration rate (GFR/nephron) and potassium and phosphate excretion was examined at three stages of progressive chronic renal failure produced in rats by sequential partial nephrectomies.
2. The adaptive increased sodium excretion per nephron in the control group receiving a constant sodium intake did not occur in the experimental group that had a gradual reduction of dietary sodium in direct proportion to the fall in GFR.
3. Despite the difference in sodium excretion, the increase in GFR/nephron, the daily variation in the amount of potassium and phosphate excreted, the increase in potassium and phosphate excretion per unit nephron, and the plasma potassium and phosphate concentrations were the same in the two groups.
4. The concept of ‘autonomous adaptation’ in chronic renal failure is presented.