Intracellular pH During Metabolic Acidosis of Intracellular and Extracellular Origin. ∗

Summary

Intracellular pH was determined by distribution of 5,5-dimethyl-2,4-oxazolidinedione (DMO) in skeletal muscle of dogs 1) infused with .3 N HCl, 2) infused with .3 N gluconic acid, 3) infused with HCl and hyperventilated to maintain extracellular fluid pH constant, 4) infused with .6 N HCO₃ and given CO₂ and O₂ to breathe to maintain extracellular pH constant, and 5) maintained in hemorrhagic shock. After the one to two hours required to reach equilibrium distribution of DMO there was not a striking difference in the intracellular hydrogen ion-extracellular hydrogen ion gradient between animals infused with HCl and those in hemorrhagic shock. Those infused with gluconic acid did show a significant difference from the shock animals. The differences were in the direction that would be expected from slower distribution across cell membranes of H⁺ and/or HCO₃- than CO_2. The experiments in which extracellular pH was maintained constant in the face of infusion of HCl or NaHCO₃ also demonstrate the primary dependence of intracellular pH on Pco₂ although in these experiments there is additional clear evidence of transfer of H⁺ or HCO₃- between intracellular and extracellular fluid over these short time intervals. With these time intervals of 1 to 3 hours, the intracellular acidosis of hemorrhagic shock is well reflected in the extracellular fluid, and the extracellular acidosis produced by infusion of acid into the blood is reflected in the intracellular fluid.