Salt restriction inhibits renal growth and stabilizes injury in rats with established renal disease.

Salt restriction inhibits renal growth and stabilizes injury in rats with established renal disease. Male Munich-Wistar rats that underwent right nephrectomy and segmental infarction of two thirds of the left kidney were fed standard chow for 4 wk and then randomly assigned to ingest standard or low-salt chow for an additional 4 wk. Four wk after ablation, rats had systemic hypertension, proteinuria, and glomerular sclerosis. The prevalence of sclerosis, protein excretion rate, and glomerular volume increased between the fourth and eighth week in rats that were fed standard chow, however, in rats that were fed low-salt chow, the increase in glomerular volume and development of further glomerular sclerosis was prevented whereas the protein excretion rate actually declined. Micropuncture studies performed 8 wk after ablation revealed that the glomerular hydraulic pressure was elevated in remnant kidneys and was not affected by salt restriction. This study demonstrates that dietary salt restriction can prevent further glomerular injury and reduce proteinuria even when instituted in rats with established renal disease. These findings are also consistent with the hypothesis that glomerular hypertrophy promotes injury in this model of hypertension and progressive renal disease.