Varying Role of Extracellular Electrolytes in Metabolic Acidosis and Alkalosis

The responses of plasma and extracellular space to different types of acids and alkalis were studied in nephrectomized cats. Compensation for mineral acids can largely be accounted for by changes which are detectable in extracellular constituents. These changes are movement of Na+ and K+ into the extracellular space (ECS) and loss of HCO3– from the ECS. Organic acids which penetrate cells rapidly and may be expected to cause an intracellular and extracellular acidosis, produce negligible changes in extracellular content of Na and K. Alkalosis produced by NaOH or NaHCO3 was compensated for mainly by extracellular gain of bicarbonate and loss of Na. The response to NH4OH was unusual in that this alkaline solution caused an acidosis with movement of K into the ECS. The site of compensation for the various acids and alkalis was indicated by a comparison of the volume of agent infused with the change in volume of the ECS. The distribution of Na in these animals was not related as much to the concentration of Na in the ECS as it was to the pH produced by the solution infused. The response of the living organism to different types of acids and alkalis is variable and seems mainly related to the distribution of the material in the body.