 They are found within the pre-BötC and act via alpha-1, alpha-2, and beta-noradrenergic mechanisms.NE induces ICAN-dependent bursting in active nonpacemakers and depolarizes CI pacemakers, increasing the frequency of their bursting.In CS pacemakers, NE increases only the amplitude of the depolarizing drive potential and the number of action potentials during the burst, but does not affect the burst frequency in CS pacemakers, unlike in CI pacemakers.Serotonergic neurons are also involved in breathing systems.