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Differential responses to hypoxia in baro‐activated CVLM neurons
Author(s) -
Mandel Daniel A,
Schreihofer Ann M
Publication year - 2007
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.21.5.a467-b
Subject(s) - rostral ventrolateral medulla , hypoxia (environmental) , medulla , medulla oblongata , neuroscience , respiratory system , premovement neuronal activity , chemistry , endocrinology , medicine , biology , anesthesia , central nervous system , oxygen , organic chemistry
Hypoxia elevates splanchnic sympathetic nerve activity (SNA) with differential effects during inspiration and expiration by unresolved central mechanisms. Pre‐sympathetic neurons in the rostral ventrolateral medulla (RVLM), which are necessary for the sympatho‐excitatory response to hypoxia, are activated by hypoxia with oscillations entrained to the respiratory cycle. GABAergic baro‐activated neurons in the caudal ventrolateral medulla (CVLM) provide the major tonic inhibition to RVLM neurons and have patterns of activity related to central respiratory drive. We examined the hypothesis that CVLM neurons are influenced by hypoxia and that the nature of their response may coincide with their pattern of respiratory modulation. We recorded from 18 baro‐activated CVLM neurons with respiratory‐related activity in choralose‐anesthetised, vagotomized, paralyzed rats. Most CVLM neurons (13/18) were activated by hypoxia induced by inhalation of 10% O2, but others (5/18) were inhibited or silenced. The response to hypoxia was related to the pattern of central respiratory‐related activity (P <0.05, Chi‐square). Most (11/13) hypoxia‐activated CVLM neurons had inspiratory‐related activity. In contrast, most (4/5) hypoxia‐inhibited neurons had expiratory‐related activity. These data provide the first evidence that the CVLM may contribute to the complex sympathetic responses to hypoxia. Support: HL075174 (AMS), AHA 0615194B (DAM).