[Transepithelial electric potential difference (tPD) in clinical medicine. Methodologic aspects of measuring potential differences in the gastrointestinal tract].

The transepithelial potential difference of the gastrointestinal mucosa as a diagnostic parameter obtains increasing importance in clinical medicine. Therefore it is necessary to consider methodical aspects of the tPD-measurement under in-vivo conditions. The current paper presents methodical considerations for instance electrode arrangement, positions, composition of the electrolyte electrodes, diffusion potentials, rate of perfusion and unstirred water layer and their influence on the tPD-measurement.