Superior laryngeal motoneurons control muscles in the larynx and recent wor
k has shown they also have axon collaterals that project to cardiac vagal n
eurons in the nucleus ambiguus. The present study was undertaken to identif
y and examine the firing properties of superior laryngeal neurons (SLNs) in
the rat. SLNs typically fired spontaneously and repetitively at a rate of
4-7 Hz. The firing was continuous and showed little bursting activity. Firi
ng evoked afterhyperpolarizations were insensitive to apamin but blocked by
charybdotoxin. The voltage-gated currents in SLNs consist of a TTX-sensiti
ve Na current and a 4-aminopyridine sensitive K current. It is likely I:hat
the activity of these neurons not only control respiratory laryngeal muscl
es, but may also provide an interaction between the respiratory system and
the control of the heart rate. (C) 2001 Elsevier Science Ireland Ltd. All r
ights reserved.