Neutralization of infused acid by nephrectomized dogs.

From 8 to 15 mM of strong mineral acid per kilogram of body weight may be infused intravenously in the dog over a period of a few hours to produce a severe but non-fatal acidosis. Van Slyke and Cullen (1) showed that only one-sixth of the infused acid is neutralized by blood buffers, five-sixths presumably being neutralized by bicarbonate in interstitial fluid and lymph and by intracellular phosphate and proteinate buffers. Recently, Bergstrom and Wallace(2) have indicated that sodium and potassium on the surface of bone crystals are also available for neutralization of acid. How tissue buffers participate in the neutralization of acid has been investigated by measuring changes in total quantity of extracellular sodium, potassium, bicarbonate, and chloride ions following infusion of hydrochloric acid into nephrectomized dogs. Our preliminary reports (3, 4) were based on experiments in which extracellular fluid volume was approximated by inulin distribution. The observation of a considerable increase in the inulin volume of distribution following infusion of acid led us to compare volumes of distribution of several substances proposed by others as approximations of extracellular fluid volume. This comparison indicated that radiosulfate distribution more closely measures extracellular fluid volume than does inulin in the whole animal (5). Therefore, the experiments on the effects of hydrochloric acid infusion have been repeated using radiosulfate distribution to measure changes in extracellular fluid volume. No definitive publication of the original experiments is contemplated. The results of our recent experiments indicate that when 10 mM of hydrochloric acid per kilogram of body weight are infused into a nephrectomized dog over a period of two hours, 43 per cent of the infused acid is neutralized by bicarbonate