Correction of metabolic alkalosis by HCl and acetazolamide: effects on extracellular and intracellular acid-base status in rats in vivo.

Extracellular plasma pH (pHe) of nephrectomized male or female Sprague-Dawley rats was changed by infusion of either sodium bicarbonate or HCl to predetermined values in the pH range of 7.53-7.14, and then held constant for 2 h. Intracellular pH (pHi) of the liver, heart, brain, and two skeletal muscle groups as calculated from the distribution of 14C-labelled DMO (5.5-dimethyl-2,4-oxazolidinedione) was compared to corresponding tissues of a control group and rats treated with the carbonic anhydrase inhibitor acetazolamide (Diamox). When compared to control, changes of the extracellular pH in male or female rats were followed by similar effects on pHi in the investigated tissues. At the same extracellular pH there were no statistical differences between pHi values of HCl or acetazolamide treated rats, though the arterial PCO2 following acetazolamide administration was significantly increased when compared to control or the corresponding HCl group. This study shows that administration of acetazolamide or HCl results in a dose-dependent decrease of plasma and tissue pH, and that both agents may be used as a logical and safe therapy during severe metabolic alkalosis in rats.