Acid-base alterations and plasma potassium concentration

Abstract

Arterial pH of anesthetized dogs was held constant during infusion of HCl or NaHCO₃ by appropriate alterations in alveolar ventilation. While plasma potassium concentration dropped somewhat (presumably due to gradual potassium depletion), there was no significant difference in plasma potassium during the two types of infusions. The implication is that metabolic and respiratory acid-base disturbances having comparable effects on pH also have similar effects on the plasma potassium concentration. Other data support this conclusion and also indicate that effects of acidosis and alkalosis are quantitatively similar. On the basis of data of this study and of other data in the literature, it appears that the ratio of change in potassium concentration to change in blood pH ordinarily averages –3.0 to –5.0 in a steady state and that achieving a steady state requires 1–2 hours of equilibration. Data are presented which support the concept that extracellular K concentration, rather than total extracellular K, is physiologically regulated and that this involves rapid exchanges with intracellular K.