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Sodium Cyanide And Hypoxic Hypoxia Elicit Similar Modulation Of Hypoglossal Motor Output In Neonatal Rat Transverse Medullary Slice
Author(s) -
Wilson Christopher G,
Shafer Geoffrey O,
Solomon Irene C
Publication year - 2006
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.20.4.a787-c
Subject(s) - sodium cyanide , hypoxia (environmental) , tonic (physiology) , chemistry , stimulation , slice preparation , perfusion , anesthesia , medullary cavity , endocrinology , medicine , cyanide , oxygen , central nervous system , inorganic chemistry , organic chemistry
In the in vitro transverse medullary slice preparation that contains the pre‐Bötzinger complex (pBc), severe hypoxia (95%N 2 /5%CO 2 ) elicits a biphasic response, consisting of augmentation followed by depression, in inspiratory‐related rhythmic discharges. Focal application of sodium cyanide (NaCN, often used as a surrogate for producing tissue hypoxia), into the in vivo pBc produces a robust stimulation of phasic inspiratory motor output. It remains to be determined whether the respiratory motor response to NaCN in the in vitro medullary slice preparation is similar to that of hypoxic hypoxia. To assess this, we recorded hypoglossal (XII) rootlet activity in response to bath application of NaCN (100–300 μM) or hypoxic hypoxia (94%N 2 /1% O 2 /5%CO 2 ) in 4 neonatal rat (P1–P4) slice preparations (350–450μm). In a subset of slices, we also tested focal application of NaCN (1 mM, ~2–5 nl) into the pBc or XII nucleus. In response to perfusion with either NaCN or hypoxic hypoxia, an increase in XII burst frequency of 32±7 (100 μM NaCN), 75±27 (300 μM NaCN), and 86±14% for (hypoxic hypoxia) followed by tonic discharge was observed. Focal application of NaCN into the pBc (n=5 sites) elicited an increase in burst frequency by 45±4% while focal application into the XII nucleus (n=3 sites) produced a lower magnitude tonic discharge. Our results suggest that NaCN mimics the effects of hypoxic hypoxia on XII discharge in the slice preparation, and provide additional support to the concept of intrinsic hypoxic chemosensitivity in the pBc. Supported by HL62527, HL63175