Microiontophoresis of flurazepam on inspiratory and postinspiratory neurons in the ventrolateral medulla of cats: An intracellular study in vivo

Abstract

Effects of flurazepam on the periodic inhibitory postsynaptic potentials (IPSPs) and on the action of locally applied γ-aminobutyric acid (GABA) were studied in bulbar respiratory neurons of decerebrate cats using concentric multibarrelled electrodes for intracellular recording and extracellular iontophoresis. Iontophoresis of flurazepam augmented spontaneous IPSPs and increased the hyperpolarization induced by GABA. Iontophoretic application of bicuculline suppressed the action of flurazepam. The reversal potential for spontaneous IPSPs was similar to that for the GABA-response. Intracellular Cl − injection shifted both the IPSP wave and the GABA response in a depolarizing direction. Flurazepam enhanced these depolarizing responses. These results suggest that GABA mediates the postsynaptic inhibition in bulbar respiratory neurons.