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Hypoventilation in awake goats following unilateral lesions in the rostral ventrolateral medulla (RVLM) targeted by surface cooling‐induced apnea.
Author(s) -
Miller Justin,
Neumueller Suzanne,
Marshall Brooke,
Baogang Qian,
Mouradian Gary,
Hodges Matthew,
Pan Lawrence,
Forster Hubert
Publication year - 2010
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.24.1_supplement.799.27
Subject(s) - anesthesia , control of respiration , rostral ventrolateral medulla , medicine , apnea , tidal volume , ventilation (architecture) , respiratory system , peripheral chemoreceptors , medulla oblongata , hypoventilation , respiratory center , central sleep apnea , chemoreceptor , central nervous system , receptor , polysomnography , mechanical engineering , engineering
Thirty seconds of cooling the RVLM induces apnea and reduced breathing in anesthetized and awake goats, respectively (J Appl Physiol 78: 247–257, 1995). We recently studied the effects on breathing in two goats of unilateral ibotenic acid (IA: 1 μl) induced RVLM lesions 1 mm below the medullary surface at a critical site identified by cooling under anesthesia. Upon recovery from anesthesia, both goats hyperventilated at rest for 5 days, but thereafter hypoventilated (PaCO 2 8–10 mmHg above control) for several days due to decreased tidal volume and breathing frequency. In one goat CO 2 sensitivity was attenuated nearly 50% during the period of hypoventilation, but the ventilatory responses to hypoxia and exercise, and breathing during NREM sleep were unaffected. In this goat resting PaCO 2 and CO 2 sensitivity returned to control about 15 days post‐lesion. Both goats were in excellent health throughout the post surgery period. Post‐mortem histology indicated the lesioned sites were in an area of high density neurokinin‐1 receptor expressing neurons, near or including the retrotrapezoid nucleus. These data suggest that neurons near the RVLM surface are necessary to maintain normal levels of eupneic breathing, and contribute to respiratory CO 2 chemoreception.