Kinetic properties of the sodium current in periglomerular (PG) cells were investigated by applying whole-cell patch-clamp techniques to thin slices of the frog olfactory bulb. Eight of the cells were intracellularly stained with Lucifer Yellow for precise identification. Under current-clamp conditions PG cells showed rich spontaneous activity at rest. Na current was isolated from other current contributions by equimolar substitution of K+ with Cs+ in the intracellular solution to prevent K-currents, and 100 microM Cd2+ in the external solution to block Ca-current. Depolarisations beyond -40 mV activated a fast transient TTX-sensitive inward current. Once activated, INa declined exponentially to zero following a single exponential. The underlying conductance showed a sigmoidal activation between -40 and +30 mV, with half activation at -17.4 mV and a maximal value of 9.7 nS per neurone. The steady-state inactivation was complete at -30 mV and completely removed at -90 mV, with a midpoint at -56 mV. The activation process could be adequately described by third order kinetics, with time constants ranging from 260 microseconds at -20 mV to 70 microseconds at +50 mV.

Sodium current in periglomerular cells of frog olfactory bulb in vitro

BELLUZZI, Ottorino
1995

Abstract

Kinetic properties of the sodium current in periglomerular (PG) cells were investigated by applying whole-cell patch-clamp techniques to thin slices of the frog olfactory bulb. Eight of the cells were intracellularly stained with Lucifer Yellow for precise identification. Under current-clamp conditions PG cells showed rich spontaneous activity at rest. Na current was isolated from other current contributions by equimolar substitution of K+ with Cs+ in the intracellular solution to prevent K-currents, and 100 microM Cd2+ in the external solution to block Ca-current. Depolarisations beyond -40 mV activated a fast transient TTX-sensitive inward current. Once activated, INa declined exponentially to zero following a single exponential. The underlying conductance showed a sigmoidal activation between -40 and +30 mV, with half activation at -17.4 mV and a maximal value of 9.7 nS per neurone. The steady-state inactivation was complete at -30 mV and completely removed at -90 mV, with a midpoint at -56 mV. The activation process could be adequately described by third order kinetics, with time constants ranging from 260 microseconds at -20 mV to 70 microseconds at +50 mV.
1995
Bardoni, R.; Magherini, P. C.; Belluzzi, Ottorino
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1394577
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