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Central chemoreceptors modulate breathing via multipath tuning in ventrolateral respiratory column (VRC) circuits
Author(s) -
Lindsey Bruce,
Ott Mackenzie M.,
Nuding Sarah C.,
Segers Lauren S.,
O'Connor Russell,
Morris Kendall F.
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.847.27
Unknown VRC circuit mechanisms tune breathing in response to changes in central chemoreceptor drive. We tested the hypothesis that multiple local circuit pathways are concurrently modulated by chemoreceptor influences. Multi‐array recordings, spike‐train cross‐correlation, and spike‐triggered averaging of phrenic nerve activity were used in 7 decerebrate, vagotomized, neuromuscularly blocked, and artificially ventilated cats. Central chemoreceptors were stimulated by injection of CO 2 ‐saturated saline into the vertebral artery. Results support the following interactions: Inspiratory (I) drive is transmitted via rostral‐to‐caudal excitatory neuron chains. These chains are modulated by I neurons that inhibit not only other excitatory and inhibitory I neurons but also peri‐columnar “tonic” expiratory (E) neurons. Tonic E neurons inhibit I neurons, influencing phrenic motor output (indicated by time‐locked reductions in spike‐triggered averages). Caudal I and E VRC populations are also modulated by retrotrapezoid nucleus/parafacial region (RTN‐pF) neurons. We conclude that RTN‐pF cells and peri‐columnar tonic expiratory neurons are elements of a multipath architecture that dynamically tunes network activity and premotor outputs in response to changes in central CO 2 /pH levels. Support by NIH grant R37 NS019814.