DIETARY SUPPLEMENTATION OF L-ARGININE AMELIORATES RENAL HYPERTROPHY IN RATS FED A HIGH-PROTEIN DIET

Ingestion of a high-protein diet or intravenous administration of amin o acids is associated with an increase in glomerular filtration rate ( GFR). It can also lead to renal hypertrophy, and, if sustained, may ca use glomerular sclerosis. L-Arginine administration ameliorates the pr ogression of renal disease in rats with subtotal nephrectomy and preve nts the increase in GFR observed in rats with experimental diabetes. T he present study examines the potential effect(s) of L-arginine admini stration (1%) in the drinking water on the renal hypertrophy that occu rs in rats fed a high-protein diet for 1 month. Four groups of female Sprague-Dawley rats, six in each group, were studied (95 +/- 1 g). Gro ups 1 and 2 were fed a low-protein diet (12% casein, 0.504% L-arginine ); Group 1 was given tap water, whereas Group 2 was given tap water su pplemented with L-arginine. Groups 3 and 4 were fed a high-protein die t (40% casein, 1.68% L-arginine); Group 3 was given tap water, whereas Group 4 was given tap water supplemented with L-arginine. The rats ha d free access to food and water during the study period. The kidney we ight and the kidney to body weight ratio of rats of Group 3 were signi ficantly greater than in the other groups of rats. Renal hypertrophy w as prevented in the rats of Group 4. The excretion of erotic acid in t he urine, an index of L-arginine deficiency, was significantly greater in rats of Group 3 than in rats of Group 4. Thus, the renal hypertrop hy that occurs in rats fed a high-protein diet was decreased in rats g iven L-arginine supplementation in the drinking water. This effect was associated with less excretion of erotic acid in the urine in rats gi ven L-arginine. A relative deficiency of L-arginine may occur during h igh-protein feeding that may shunt nitrogen metabolism from the urea c ycle to the erotic acid pathway.