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Synaptic and intrinsic activation of respiratory GABAergic neurons in the brainstem
Author(s) -
Frank Julie G,
Mendelowitz David
Publication year - 2011
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.25.1_supplement.1077.15
Subject(s) - gabaergic , brainstem , neuroscience , respiratory system , chemistry , medicine , biology , anatomy , inhibitory postsynaptic potential
Respiratory sinus arrhythmia is mediated by inspiratory‐evoked increases in GABAergic neurotransmission to cardiac vagal neurons (CVNs) that control heart rate. However, the mechanisms responsible for the sources and activation of the inspiratory‐related GABAergic neurotransmission to CVNs are unknown. We identified a population of GABAergic neurons in the ventrolateral medulla that are activated during inspiration in a slice preparation that retains rhythmic respiratory activity. This population of inspiratory‐activated GABAergic neurons receives inspiratory‐related excitatory events that were blocked by the glutamatergic antagonists, NMDA and AMPA/kainate receptor antagonists AP‐5 and CNQX, respectively. The nicotinic acetylcholine receptor antagonists, DHbE, 100microM and a‐BTX, 100nM had no significant effect. A subset of inspiratory GABAergic neurons continue to fire in the presence of CNQX/AP‐5, suggesting they may have the characteristics of a respiratory pacemaker neuron. The pacemaker cells not inhibited by CNQX were insensitive to cadmium. The results from this study demonstrate the existence of a population of GABAergic inspiratory neurons in the ventrolateral medulla that likely project to CVNs, receive increased glutamatergic neurotransmission during inspiration, and a subset of these GABAergic neurons have respiratory pacemaker properties.