The Renal Sodium Excretion During Oral Hydration in Man

Abstract

The effect of a moderate oral hydration in combination with inhibition of the activity of endogenous antidiuretic hormone has been investigated in 12 normal persons. Special care was taken to avoid major changes in the steady state of extracellular volume. The application of 10 ml/kg water initially with rehydration by giving 5mi/kg every 60 min. up to a total of 4 hrs. is followed by an increasing renal sodium and chloride excretion in spite of the constancy of tubular sodium load (creatinine clearance times serum sodium concentration) and urine volume. The urinary potassium excretion also increases during the duration of the experiment. The possible mechanism of this "natriuretic effect" is discussed.