Generation and transmission of respiratory oscillations in medullary slices: role of excitatory amino acids

• DOI: 10.1152/jn.1993.70.4.1497
• Publication Date: 2017-12-25T02:27:25Z
• Authors: G. D. Funk; J. C. Smith; J. L. Feldman
• Keywords: CNQX; Rostral ventrolateral medulla; Respiratory center; Medulla; Slice preparation

1. The involvement of excitatory amino acid (EAA) receptors in the generation respiratory rhythm and transmission inspiratory drive to hypoglossal (XII) motoneurons was examined an vitro neonatal rat medullary slice preparation. Slices generated rhythmic activity XII nerves. role EAAs determined by analyzing perturbations network after bath application EAA receptor antagonists or local microinjection into main column neurons ventrolateral medulla (ventral group), particularly pre-Bötzinger complex (pre-BötC). recording nerve discharge motoneuron synaptic inputs either motor nuclei sites containing interneurons circuit. 2. Block non-N-methyl-D-aspartate (non-NMDA) 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reversibly reduced burst frequency amplitude a concentration-dependent manner, completely blocking output at concentrations > 4 microM. Activation 2-amino-4-phosphonobutyric (AP-4)-sensitive with D,L AP-4 30% but did not alter frequency. NMDA channels (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-iminemaleate (MK-801) perturb output. Inhibition uptake slices dihydrokainic increased discharge. 3. non-NMDA multiple along medulla, including pre-BötC, unilateral CNQX produced dose-dependent, bilateral reduction without substantial oscillations. within pre-BötC ventral altering ultimately block 4. Non-NMDA nucleus dose-dependent ipsilateral perturbing Perturbations contralateral were significantly smaller. channel affect amplitude, whereas activation caused amplitude.