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Non‐NMDA receptor activation in the Nucleus Tractus Solitarius (NTS) increases ventilatory drive
Author(s) -
Carr J. Austin,
Fu Zhenxing,
Powell Frank L.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.954.5
Subject(s) - hypoxic ventilatory response , nmda receptor , microinjection , ventilation (architecture) , glutamate receptor , receptor , anesthesia , microinjections , medicine , endocrinology , chemistry , respiratory system , mechanical engineering , engineering
Previous studies showed an important role for N‐methyl‐D‐aspartate (NMDA) receptors but not non‐NMDA receptors in the NTS in the hypoxic ventilatory response (HVR) of awake rats. We hypothesized that plasticity of non‐NMDA receptors in the NTS is necessary for ventilatory acclimatization to hypoxia, which increases normoxic ventilatory drive and the acute HVR. To test this, we microinjected artificial CSF or NBQX in the NTS (4 mM in 50 nL, bilaterally) of normoxic control rats (CON, n=7) and chronically hypoxic rats (CH, n= 3, P IO2 = 70 Torr for 7 days) and used barometric pressure plethysmography to measure ventilation. Microinjection sites were identified by colloidal gold microinjections after the experiment. Ventilation (ml/(kg min) was (mean + sem): Non‐NMDA receptor blockade significantly (P<0.05) decreased ventilation under all conditions with no significant interactions between drug and treatment or inspired O 2 . Ventilatory changes resulted from significant effects on breathing frequency but not tidal volume. Hence, non‐NMDA receptors in the NTS are important for ventilatory drive under normoxic and hypoxic conditions but they are not solely responsible for ventilatory acclimatization to hypoxia. Supported by R01‐ HL081823 (FLP) and The American Physiological Society (JAC).