Diffusion Potentials and Potassium Distribution across the Gallbladder Wall *

Abstract

Potential differences were measured across in vivo and in vitro rabbit gallbladders and were found to be directly related to sodium concentration in the mucosal bathing solution. Theoretical bile-serum potassium distribution was then calculated from the Nernst equation. Potassium activities in sulphate test solutions and bile were estimated from previously derived activity coefficients determined by sodium- and potassium-selective glass electrodes. A close correlation was found between observed potassium activities and those predicted by the Nernst equation according to existing electrochemical gradients. There was no evidence of an active "secretory" process. The data suggest that the high potassium levels in concentrated gallbladder bile result from passive transport phenomena.