Changes in biophysical properties in mitral cells following insulin application.

* = Significantly-different mean values via paired t-test, α≤0.05. Insulin measurements represent the 20 minute time point following bath application of 0.1 µM (1 µg/mL) insulin. τInact = the inactivation time constant, τDeact = the deactivation time constant, spike frequency = calculated throughout step depolarization, intraburst frequency = calculated during spike cluster, ISI = interspike interval within a spike cluster, action potential cluster = defined as three or more action potentials with less than 100 ms pause duration, pause duration = duration between clusters, 1/e = action potential decay time. Voltage-activated currents were measured using a Vh = -80 mV with a depolarizing Vc = +40 mV of 400 ms in duration and an interpulse interval of 30-45 s. In voltage-clamp recordings in which tetrodotoxin was not applied, a sustained/transient ratio was determined when spiking prevented subsequent kinetic analysis. In current-clamp recordings, firing properties were determined using a perithreshold current injection of 25 pA and 5000 ms duration. Action potential properties were determined using a 200 pA current injection of 1000 ms duration using a 50 µs sampling frequency.