DISSOCIATED ADULT-RAT SUBFORNICAL ORGAN NEURONS MAINTAIN MEMBRANE-PROPERTIES AND ANGIOTENSIN RESPONSIVENESS FOR UP TO 6 DAYS

We have utilised standard dissociation techniques to obtain a preparat ion of subfornical organ (SFO) cells that have been maintained in tiss ue culture for up to 1 week. Stable (>15 min) whole cell recordings we re obtained from 80 cells displaying rapid (<2 ms) voltage-dependent s odium currents (blocked by tetrodotoxin in 10 of 10 cells tested), and current evoked action potentials, which were thus classified as SFO n eurons. 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 res istance of 1.2 +/- 0.1 G Omega, characteristics which did not change s ignificantly in recordings obtained for up to 6 days after dissociatio n. Current clamp recording showed that of 65 cells tested with bath ap plication of angiotensin (ANG; 1,000-10 nM), 41 responded to this pept ide 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 v iable cells up to 6 days after initial cell dissociation. These studie s provide the first description of the basic membrane properties of di ssociated SFO neurons. The responsiveness of these cells to ANG suppor ts the conclusion that their properties are similar to those in vivo. These data suggest that use of this technique will permit systematic a nalysis of the membrane events underlying the actions of multiple liga nds on this uniquely specialised group of CNS neurons.