Renal excretion of urea and electrolytes in sheep and red deer.

1. The effects of varying the intake of water and nitrogen on the renal excretion of urea and electrolytes has been studied in sheep and in red deer.2. The concentration of urea in the urine of both sheep and deer decreased as the volume of urine increased and about eight times as much urea was excreted each day when a high-nitrogen diet was fed compared to when a low-nitrogen diet was fed.3. Both the concentrations of sodium and potassium in the urine decreased as the urine volume increased but the total amounts excreted were independent of urine volume.4. The osmotic concentration of the urine decreased as urine volume increased.5. In both deer and sheep the concentration of urea in the plasma was considerably higher when a high-nitrogen diet was fed compared to when a low-nitrogen diet was fed but the rate of clearance of inulin from the plasma did not appear to be related to the diet.6. Appreciably more urea was filtered at the glomerulus when a high-nitrogen diet was fed compared to when a low-nitrogen diet was fed but the percentage of filtered urea reabsorbed was not related to diet.7. The results indicate no qualitative differences between deer and sheep in the renal excretion of urea and electrolytes.