Potassium permeability in the absence of fluid reabsorption in proximal tubule of the anesthesized rat

A luminal microperfusion technique was used to examine the K+ permeability of surface proximal convoluted tubules (PCT) in the kidney of anesthetized rats. Transtubular potassium concentration (AK+B) gradients were varied by altering the concentration of KCl in luminal perfusates, to which 32 mmol/l of the impermeant solute raffinose, was also added to prevent net fluid reabsorption.