Sodium bicarbonate, sodium lactate and Tris in the treatment of metabolic acidosis: Effects on intracellular pH and electrolyte content of voluntary muscle

Abstract

Acute metabolic acidosis was produced in bilaterally nephrectomized rats by the intravenous infusion of 5 mM/Kg. HCl (as 0.3 N HCl) for 1 to 2 hours. This was followed by infusion of either 0.9 per cent NaCl, 0.3 M NaHCO 3, 0.3 M Na lactate or 0.3 M Tris for 1 2 to 1 hour. The amount given was 5 mM/Kg. except for the NaCl, in which the amount given was 2.5 mM/Kg. The effects on extracellular and intracellular acid-base balance and on the electrolyte content of plasma and voluntary muscle were studied. Intracellular pH (pHi) of voluntary muscle was obtained from the distribution of the weak acid 5,5-dimethyl-2,4-oxazolidinedione (DMO) between muscle and plasma. The HCl NaCl group showed acidemia (pH 7.20), but the pHi (6.97) was not significantly different from that of rats given only NaCl. NaHCO 3 and Na lactate both restored extracellular pH to normal levels without causing any significant change in pHi. In the HCl Tris group, extracellular pH (7.30) was not restored to normal. Tris caused respiratory depression and, in addition, raised slightly the plasma potassium. Under the conditions of this experiment, NaHCO 3, and Na lactate were equally effective in the treatment of acute metabolic acidosis. Equal amounts of Tris were less successful.