Simultaneous recordings of the activity of phrenic nerve (PN) and BötC post-I neurones of control (Aa) and SH rats (Ab), representative of their respective groups. In Ac, the intracellular recordings of post-I neurones of control and SH rats are superimposed. Note that the firing frequency of the post-I neurone of SH rat is reduced in comparison to control. In the presence of fast synaptic blockade, input resistance (Ri; Ba, b and c) and intrinsic excitability (Ca, b and c) were not different between control and SH rats. Ia: Current.