Effect of sodium and potassium ingestion on renal growth in rats

To determine whether differences in dietary Na and K intake influence renal growth and compensatory renal growth following unilateral nephrectomy (uni), rats were given 2 diets for 2 weeks which differed only in Na-K concentrations. Diet 1 (High Na, Low K) contained 1.0% Na, 0.36% K and diet 2 (Low Na, High K) contained 0.05% Na, 2.0% K. Half of the rats consuming diets 1 and 2 for 1 week received uni and the other half of sham operation (sham). The rats were followed for another week while consuming the experimental diets. Uni and sham rats on diet 1 showed significant increase in blood pressure (BP) (136 +/- 4 v 126 +/- 3 mm Hg, P less than .05). Uni itself did not alter blood pressure. Body weight and heart rate were unchanged by diet or operation. Kidney weight, renal RNA, protein, RNA/DNA, and protein/DNA increased significantly after uni but the differences were not affected by diet. Serum blood urea nitrogen (BUN) and creatinine were not markedly different among any group of rats suggesting no major renal damage. We conclude that dietary changes of Na-K which cause no obvious renal damage even though BP is elevated moderately do not influence renal growth or compensatory renal growth. Based on RNA, DNA and protein metabolism, the form of growth (hypertrophy or hyperplasia) is also not influenced by renal electrolyte handling.