Respiratory control by ventral surface chemoreceptor neurons in rats.
A long-standing theory posits that central chemoreception, the CNS mechanism for CO(2) detection and regulation of breathing, involves neurons located at the ventral surface of the medulla oblongata (VMS). Using in vivo and in vitro electrophysiological recordings, we identify VMS neurons within the rat retrotrapezoid nucleus (RTN) that have characteristics befitting these elusive chemoreceptors. These glutamatergic neurons are vigorously activated by CO(2) in vivo, whereas serotonergic neurons are not. Their CO(2) sensitivity is unaffected by pharmacological blockade of the respiratory pattern generator and persists without carotid body input. RTN CO(2)-sensitive neurons have extensive dendrites along the VMS and they innervate key pontomedullary respiratory centers. In brainstem slices, a subset of RTN neurons with markedly similar morphology is robustly activated by acidification and CO(2). Their pH sensitivity is intrinsic and involves a background K(+) current. In short, the CO(2)-sensitive neurons of the RTN are good candidates for the long sought-after VMS chemoreceptors.
Mulkey
Daniel K
DK
Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA.
Stornetta
Ruth L
RL
Weston
Matthew C
MC
Simmons
Johnny R
JR
Parker
Anson
A
Bayliss
Douglas A
DA
Guyenet
Patrice G
PG
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002245:Carbon Dioxide / Q000502:physiology; D002628:Chemoreceptor Cells / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012125:Respiratory Center / Q000187:drug effects / Q000502:physiology*
D002245:Carbon Dioxide; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione