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Further evidence of redox modulation of neurons in a CO 2 ‐chemosensitive area: normobaric hyperoxia (95%O 2 ) stimulates CO 2 ‐chemosensitive and –insensitive neurons in the solitary complex (SC)
Author(s) -
Matott Michael Patrick,
Landon Carol S,
Putnam Robert W,
Dean Jay B
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.1026.14
Subject(s) - hyperoxia , hypercapnia , chemistry , oxygen , anesthesia , endocrinology , medicine , respiratory system , organic chemistry
We previously reported that CO 2 ‐excited neurons in SC, in medullary slices maintained in 95%O 2 , are stimulated by chemical oxidants and hyperbaric O 2 (JAP 95:910‐921, 2003; AJP 286:C940–951, 2004). Here we test the hypothesis that SC neurons, maintained in 40%O 2 rather than 95%O 2 (to reduce oxidative stress), are viable and stimulated by normobaric hyperoxia (95%O 2 ). Slices (P1–21) were harvested in chilled ACSF gassed with 95%O 2 and immediately transferred to ACSF (22–24°C) equilibrated with 40%O 2 ‐5%CO 2 in N 2 . Whole cell recordings (35–37°C) were established in 40%O 2 (n=44) and tested using hyperoxia (40→95%O 2 ) and hypercapnia (5→10 or 15%CO 2 ). Hyperoxia stimulated 8/44 neurons and hypercapnia stimulated 5/44 neurons; of these 4/8 were stimulated by both O 2 and CO 2 . Hyperoxia usually increased firing rate and decreased input resistance whereas hypercapnia increased firing rate and input resistance. Most neurons tested were insensitive to hyperoxia and hypercapnia (31/44). Compared to previous slice studies that used 95%O 2 control, there is a smaller proportion of CO 2 ‐excited SC neurons in slices maintained in 40%O 2 . These data indicate that medullary slices are viable in 40%O 2 and that hyperoxic stress stimulates SC neurons, including CO 2 ‐excited neurons. These data also suggest that oxidative stimuli increases the incidence of CO 2 ‐chemosensitivity in SC neurons (ONR N000140110179, NIH R01HL56683)