Fig. 3.

Bath application of Physo (10 μM) induced a tonic inward current, increased membrane noise, decreased the amplitude of phasic inspiratory drive current, increased the frequency of sEPSCs and decreased the input resistance in preBötC inspiratory neurons. Physo also increased respiratory frequency, the amplitude and duration of integrated inspiratory bursts of hypoglossal nerve. (A) Im, membrane current of inspiratory neuron voltage-clamped at −65 mV. (B) Phasic inspiratory drive current of an inspiratory neuron voltage-clamped at −65 mV in Ctrl and Physo conditions. Each trace was an average of five consecutive inspiratory periods triggered by the upstroke of the integrated inspiratory bursts from XIIn and the Im trace was low-pass filtered at 20 Hz. (C) sEPSCs during expiratory periods on an extended time scale; a and b correspond to the times labeled a and b in panel A. (D) Summary of the effects of Physo on XIIn rhythmic activity and on inspiratory neurons (mean±S.E.). The parameters of XIIn rhythmic activity include Frq, Amp and duration of integrated inspiratory bursts. The parameters of inspiratory neurons include Insp Amp and duration, Input R, sEPSC Frq and sEPSC Amp. * Statistical significance during Physo application vs. pre-Physo control (paired t-test). Numbers of neurons (n) for every experiment are indicated in the text of Results section.