We have utilised standard dissociation techniques to obtain a preparation of subfornical organ (SFO) cells that have been maintained in tissue culture for up to 1 week. Stable (> 15 min) whole cell recordings were obtained from 80 cells displaying rapid (<2 ms) voltage-dependent sodium currents (blocked by tetrodotoxin in 10 of 10 cells tested), and current evoked action potentials, which were thus classified as SFO neurons. These neurons had a resting membrane potential of-63.8 +/- 1.3 mV (mean +/- SEM), spike amplitude of 86.8 +/- 2.5 mV, and input resistance of 1.2 +/- 0.1 G omega, characteristics which did not change significantly in recordings obtained for up to 6 days after dissociation. Current clamp recording showed that of 65 cells tested with bath application of angiotensin (ANG; 1,000-10nM), 41 responded to this peptide with decreases in input resistance (control 1.4 +/- 0.16 G omega, after ANG 0.78 +/- 0.1 G omega, p < 0.0001), and depolarisations (mean 18.3 +/- 2.0 mV, p < 0.0001). Similar recordings were obtained from viable cells up to 6 days after initial cell dissociation. These studies provide the first description of the basic membrane properties of dissociated SFO neurons. The responsiveness of these cells to ANG supports the conclusion that their properties are similar to those in vivo. These data suggest that use of this technique will permit systematic analysis of the membrane events underlying the actions of multiple ligands on this uniquely specialised group of CNS neurons.