Volgin D. Investigation of the medullary regulatory mechanisms of respiratory rhythmogenesis in newborn rats involving nitric oxide and N-methyl-D-aspartate receptors

NADPH-diaphorase positive neurons were found in all nuclei of both dorsal and ventral respiratory neurons groups, the maximal density of stained cells was present in the rostral part of ventrolateral medulla (VLM) - in the region of lateral paragigantocellular reticular nucleus. It was found that endogenous NO mediates the mechanism of tonic inhibitory control of the frequency of respiratory rhythm (RR) located in the rostral VLM under normal and hypoxic conditions, involved in activation of the frequency of RR by low extracellular pH and in the generation of the basic RR by the more caudal structures of VLM. It was shown that NO biosynthesis mediates the effect of NMDA on the RR, but NO can block NMDA receptors. NMDA receptors in the VLM involved in the regulation of the RR parameters under normal, hypoxic and low extracellular pH conditions.