Comparison of intra-and extracellular buffering of clinically used buffer substances: tris and bicarbonate

A large and important group of acid-base disturbances are the metabolic acidoses. In general, every type of metabolic acidosis can be treated with infusion of base when the underlying cause of the disturbances is removed. In our medical centers, the use of tris and bicarbonate is common. For a long time they were competitive agents and until now it was not possible to decide by available clinical methods which of these substances was more suitable for correction of metabolic acidosis. The intracellular pH of the whole rat (mean lcf-pH) was determined from the distribution of 14C labelled DMO (5,5-dimethyl-2,4-oxazolidinedione) and monitored for 6 h following intravenous application of tris or sodiumbiarbonate in a dose of 10 mmol per kg body mass. Arterial plasma pH and PCO2 were also measured. To determine and compare the effectiveness of the two buffer substances, intra- and extracellular bicarbonate were calculated from the Henderson-Hasselbalch equation. It was found that the buffering following bicarbonate infusion is more effective in both body compartments. Sodiumbicarbonate should be preferred in daily practice.