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

Open Access
Publisher Website
Google Scholar
Abstract
Proximal acidification was investigated by measuring HCO3" concentration in tubular fluid in normal rats, rats made acutely alkalotic by an infusion of NaHCO3, and rats with hypokalemic alkalosis. The concentration of HCO3- in the proximal tubule of normal rats fell to an average value of 7.5 mEq per L, a value significantly lower than that of plasma. Despite a comparable degree of metabolic alkalosis in the rats given NaHCO3 and the hypokalemic rats, every sample of proximal fluid in the rats given NaHCO3 had a higher HCO3- concentration than plasma, whereas every proximal sample in the hypokalemic rats had a lower HCO3- concentration than plasma. This clearly indicates that K+ deficiency increases the capacity of the proximal convoluted tubule to reabsorb filtered HCO3-. Since K+ is not secreted in the proximal tubule, the effect of K+ deficiency cannot be due to decreased competitive inhibition at a common H+ - K+ secretory pathway. It is postulated that K+ depletion stimulates proximal H+ secretion by producing an intracellular acidosis.

This publication has 21 references indexed in Scilit: