Effect of Potassium Deficiency on the Reabsorption of Bicarbonate in the Proximal Tubule of the Rat Kidney*

Abstract

Potassium deficiency accelerates the secretion of HI ions by the kidney; in consequence the net excretion of acid (ammonia and titratable acid-bicarbonate) into the urine and the capacity to reabsorb filtered HCO3are increased (1-7). Although the precise mechanism involved has not been identified, Berliner, Kennedy, and Orloff (8), on the basis of the demonstrated reciprocal re- lationship between H4 and K+ secretion, proposed that these ions compete for a common secretory pathway in the distal nephron. Consequently, K+ depletion, by lowering the concentration of K+ at the competitive secretory site, would facilitate H+ secretion and increase the capacity of the distal tubule to reabsorb HCO3-(9).