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Updated: Dec 29, 2025

Electrophysiology on Isolated Brainstem-spinal Cord Preparations from Newborn Rodents Allows Neural Respiratory Network Output Recording
Published on: November 19, 2015
Endogenous glutamatergic inputs to the Parabrachial Nucleus/Kölliker-Fuse Complex determine respiratory rate
Angela A Navarrete-Opazo1, Denise R Cook-Snyder2, Justin R Miller3
1Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States.
Abstract:
The Kölliker-Fuse Nucleus (KF) has been widely investigated for its contribution to "inspiratory off-switch" while more recent studies showed that activation of the Parabrachial Nucleus (PBN) shortened expiratory duration. This study used an adult, in vivo, decerebrate rabbit model to delineate the contribution of each site to inspiratory and expiratory duration through sequential block of glutamatergic excitation with the receptor antagonists 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX) and d(-)-2-amino-5-phosphonopentanoic acid (AP5). Glutamatergic disfacilitation caused large increases in inspiratory and expiratory duration and minor decrease in peak phrenic activity (PPA). Hypoxia only partially reversed respiratory rate depression but PPA was increased to >200 % of control. The contribution of PBN activity to inspiratory and expiratory duration was equal while block of the KF affected inspiratory duration more than expiratory. We conclude that in the in vivo preparation respiratory rate greatly depends on PBN/KF activity, which contributes to the "inspiratory on- "and "off-switch", but is of minor importance for the magnitude of phrenic motor output.
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