KATP channels of parafacial respiratory group (pFRG) neurons are involved in H2S-mediated central inhibition of respiratory rhythm in medullary slices of neonatal rats

We recently found that hydrogen sulfide (H2S) participates in inhibitory regulation of rhythmic respiration by acting on the parafacial respiratory group (pFRG) in medullary slices of neonatal rats. The present study investigated whether ATP-sensitive potassium (K-ATP) channels are expressed in neurons of the pFRG, and, if so, whether they play a role in central regulation of respiratory activity, in particular the H2S-mediated central inhibition of respiratory rhythm in medullary slices of neonatal rats. Immunohistochemical techniques revealed that K-ATP channels are expressed in neurons of the pFRG region. Micro-injection of the K-ATP channel activator, pinacidil, into the pFRG region inhibited the discharge rhythm of hypoglossal rootlets, whereas injection of the K-ATP channel blocker, glibenclamide (Gl), had no effect. Micro-injection of the H2S donor sodium hydrosulale (NaHS) into the pFRG region produced identical inhibitory responses to those induced by pinacidil. However, combined microinjection of Gl and NaHS eliminated inhibitory effects of NaHS and converted to minor excitatory effects on the respiratory rhythm. It can be concluded that K-ATP channels of pFRG neurons are involved in the central regulation of respiratory rhythm and H2S-mediated inhibitory actions on respiratory rhythm in medullary slices of neonatal rats. (C) 2013 Elsevier B.V. All rights reserved.