THE EFFECT ON BLOOD AND URINE OF THE INGESTION OF SODIUM BICARBONATE

¹ Department of Physiology, School of Medicine, University of Leeds

O·145M NaHCO₃ given by stomach tube to conscious dogs caused a fall in plasma solids (protein), decrease in plasma Cl and increase in HCO₃; pH of the arterial blood increased but any increase of arterial P_CO2, was not significant; plasma K fell. The urine after 0·145M NaHCO₃ contained increased amounts of Na with only a small increase in Cl. The increased excretion of Na⁺ was mainly accompanied by a large excretion of HCO₃^-, and the urine became alkaline and contained little NH₄⁺. Changes in the excretion of inorganic PO₄, SO₄ and K were small.

Comparison was made with the effects of the same doses of Na given as 0·122M NaCl+0·023M NaHCO₃. This caused an equal fall in plasma solids but no change in plasma Cl, HCO₃ and K. The urinary excretion of Na⁺ increased to rates approximately the same as those produced by NaHCO₃ but the main urinary anion was Cl^-, the excretion of which was greatly increased. There was a small excretion of HCO₃^- with larger doses.

It is concluded that an important agent determining increased excretion of Na is dilution of the plasma protein, which is common to both types of experiment. The changes in plasma Cl and HCO₃ appear to be the factor which determines whether the increased excretion of Na⁺ is accompanied mainly by HCO₃^- or Cl^-.

Note:

Our thanks are due to Mr. J. Brook and Mrs. C. Twitchett for their technical assistance. Some of the apparatus used to this work was provided by a grant from the Medical Research Council.