WHOLE-CELL PATCH RECORDINGS FROM FOREBRAIN SLICES DEMONSTRATE ANGIOTENSIN-II INHIBITS POTASSIUM CURRENTS IN SUBFORNICAL ORGAN NEURONS

Whole cell patch clamp recordings have been obtained from SFO neurons in a forebrain slice preparation. Basic electrophysiological character istics recorded from these cells in current clamp mode showed a mean r esting membrane potential of -57.0 +/- 2.5 mV (+/- SEM, n = 7), mean i nput resistance of 900 +/- 110 M Ohm (n = 7), and a mean spike amplitu de of 68.6 +/- 4.1 mV (n = 7), accompanied by either irregular or no s pontaneous activity. All cells also demonstrated a delayed return to b aseline membrane potential following large hyperpolarizing current pul ses indicative of the presence of a rapidly activated transient potass ium current in these neurons. Voltage clamp recordings identified both rapid transient, and a sustained outward currents which demonstrated the characteristics of I-A and I-K respectively. While bath administra tion of angiotensin II (Ang) (10(-7) M) was without effect on I-K in 4 of 4 neurons tested, I-A was reduced by between 20 and 100% in the sa me 4 neurons. These data provide the first description of the basic el ectrophysiological characteristics of SFO neurons recorded in forebrai n slice preparations. They also provide the first direct evidence sugg esting that Ang may exert its control over the excitability of SFO neu rons through modulation of I-A in these cells.