Transepithelial potential difference of a single gill filament isolated from the crayfish Astacus leptodactylus Esch.: a new method.

A new method is described that allows in vitro perfusion and transepithelial electrical potential measurements of a single filament (3-5 mm long; 200 microns in diameter) isolated from the podobranch of the crayfish Astacus leptodactylus. An electrophysiological study was carried out on the preparation to validate this technique. The good physiological quality of the isolated filament preparation has been established and results of continuous measurements of the potential difference under two perfusion conditions are reported. Filaments were perfused with Van Harreveld physiological saline inside and either with Van Harreveld saline or artificial fresh water outside. Large potential differences up to 150 mV between inside and outside of the filament were recorded. When filaments were symmetrically perfused, the behavior of the electrical potential difference allowed two populations of filaments to be distinguished.