Site-specific hydrogen sulfide-mediated central regulation of respiratory rhythm in medullary slices of neonatal rats

► NaHS excites the respiratory rhythm of thin medullary slices. ► NaHS affects thicker slices in a biphasic manner: inhibition followed by excitation. ► The initial inhibitory effect induced by NaHS disappeared after lesion of the pFRG. ► An excitatory effect is induced by micro-injection of NaHS into the preBötC. ► An inhibitory effect is caused by an injection into the pFRG.