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Pre‐inspiratory and inspiratory hypoglossal motor output during hypoxia induced plasticity in the rat
Author(s) -
Lee KunZe,
Fuller David D
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.1042.4
Subject(s) - hypoxia (environmental) , bursting , motor unit , long term potentiation , electrophysiology , chemistry , medicine , respiratory system , cardiology , anesthesia , neuroscience , biology , anatomy , oxygen , receptor , organic chemistry
Respiratory discharge in the hypoglossal (XII) nerve is composed of pre‐inspiratory (pre‐I) and inspiratory (I) activity. Our first purpose was to test the hypothesis that hypoxia‐induced plasticity in XII motor output is differentially expressed in pre‐I vs. I XII bursting. Short‐term potentiation (STP) of XII motor output was induced in vagotomized and ventilated rats by isocapnic hypoxia. Both pre‐I and I XII discharge abruptly increased at beginning of hypoxia, and the relative increase in amplitude was much greater for pre‐I vs. I bursting. In addition, STP was expressed in I but not pre‐I bursting following hypoxia. Specifically, I activity remained elevated following hypoxia but pre‐I bursting abruptly returned to pre‐hypoxia levels. Our second purpose was to test the hypothesis that STP of I XII activity results from recruitment of silent XII motoneurons (MNs) vs. rate coding of active MNs. Single fiber recordings were used to classify XII MNs as I, expiratory‐inspiratory (E‐I), or silent based on baseline discharge patterns. STP of I XII activity following hypoxia was associated with increased discharge frequency in active I and silent MNs, but not E‐I MNs. We conclude that the expression of respiratory plasticity is differentially regulated between pre‐I and I XII activity. Moreover, both recruitment of silent MNs and rate coding of active I MNs contribute to STP of XII motor output following hypoxia.