Automated measurement of intestinal mucosa electrical parameters using a new digital clamp.Methods Find Exp Clin Pharmacol 2008; 30(8):591-8MF
Electrophysiological studies that include measurements of the electrical parameters of the epithelium offer insight into the cell's ability to react to different biological effectors and their functional viability. These parameters are commonly measured using a Ussing permeation chamber; however, most Ussing permeation chambers currently available must follow a strict operational protocol, and the type of electrodes used has to be taken into special consideration. The purpose of this study was to develop a new Ussing permeation chamber device with an automatic digital clamp which uses a microcontroller. Conventional electrodes, such as platinum or Ag/AgCl electrodes, are replaced by stainless steel 316L working electrodes. The electrode-electrolyte interface (inox-Ringer's) study was performed by impedance spectroscopy in the range of 1-10 kHz. The determination of Warburg's model electrical parameters was inferred from the Nyquist diagram. The model validation of the new digital clamp was performed experimentally on isolated segments of mouse jejunum. Two main study results should be mentioned. One is that impedance spectroscopy on stainless steel electrodes has provided Warburg's parameters, allowing the development of a transfer function model. The other is that the new digital clamp can simultaneously measure or calculate conductance, potential difference and short-circuit current. These results have also confirmed the great importance of Warburg's model for determining the electrical parameters of the electrode-electrolyte interface, and have shown that the measurement of intestinal mucosa electrical parameters can be achieved with a digital correction. Finally, the results suggest that stainless steel electrodes can be used successfully in a Ussing permeation chamber as working electrodes.