Influences of experimental uremia on the intra- and extracellular acid-base status of the rat.

In an experimental study the influences of beginning uremia were studied in nephrectomized rats. It was observed: (1) Though there was found a continuous decrease of extracellular pH due to accumulation of fixed acids there was a slight increase of intracellular pH resulting from concomitant hypocapnia. (2) There was found a constant loss of bicarbonate from the extra- and intracellular body compartment which was much more pronounced for the extracellular space. This loss of bicarbonate reflects the progressing metabolic acidosis and demonstrates that the intracellular compartment is more protected against an increase of hydrogen ion concentration than the extracellular space is. (3) The stability of the intracellular acid-base status during uremic metabolic acidosis arises the question whether our clinical practice with alkali substitution according to the Mellemgard-Astrup equation is still adequate in these cases. (4) Blood-gas analysis can only give information about the acid-base status of the extracellular body compartment. The large intracellular space which is the aim of our clinical therapy is excluded from these measurements. Simple reliance of blood-gas analysis may lead to wrong conclusions and mistakes in therapy.