RENAL RESPONSE OF SHEEP FED A LOW-PROTEIN DIET TO INTRAPORTAL INFUSION OF ARGININE AND GLYCINE

The renal effects of infusions of arginine and glycine into the portal vein were studied in the anaesthetized sheep with a reduced glomerula r filtration rate (GFR) after 6 weeks of low dietary protein intake. A rginine significantly elevated urine flow(V), whole kidney GFR and the amount of urea excreted (U-urea V) concomitantly with plasma urea lev el (P-urea) without changes in fractional urea excretion (FE(urea)). S heep infused with glycine showed significantly increased urinary flow only. Free-flow micropuncture of the late proximal tubule revealed tha t both the fluid flow and single nephron GFR were increased by arginin e without any significant changes in tubular fluid to plasma inulin ra tio. There was no effect of glycine on the micropuncture parameters of the sheep kidney. These results suggest that the synthesis of urea fr om arginine in the liver and its subsequent delivery to the kidney may be involved in the regulation of dietary induced changes of the glomer ular filtration rate in sheep.