1. Total body, intracellular, and extracellular electrolyte and acid-base changes were studied following sodium nitrate-induced potassium and chloride depletion and subsequent selective chloride repletion.
2. It was found that potassium and chloride depletion was associated with markedly decreased extracellular Na, K, Cl and water content. Intracellular Na increased, intracellular K decreased and there was a large transcellular redistribution of acid, i.e. extracellular alkalosis and intracellular acidosis ensued.
3. Selective chloride repletion was associated with return of extracellular pH towards normal. Extracellular K and intracellular parameters showed very little change. Further chloride administration was followed by extracellular acidosis, but extracellular K remained low.
4. There was close relationship between extracellular chloride and hydrogen ion concentrations ([Cl−]e and [H+]e) and extracellular potassium and intracellular hydrogen ion ([K+]e and [H+]i) but not between any of the other parameters. The close relationship between [H+]e and [Cl−]e may be explained by the chemical relationship between [H+]e, Pco2, and [HCO3−]e and empirical relationships between [Cl−]e and [HCO3−]e, and Pco2 and [HCO3−]e.