Distinct rhythm generators for inspiration and expiration in the juvenile rat.
Inspiration and active expiration are commonly viewed as antagonistic phases of a unitary oscillator that generates respiratory rhythm. This view conflicts with observations we report here in juvenile rats, where by administration of fentanyl, a selective mu-opiate agonist, and induction of lung reflexes, we separately manipulated the frequency of inspirations and expirations. Moreover, completely transecting the brainstem at the caudal end of the facial nucleus abolished active expirations, while rhythmic inspirations continued. We hypothesize that inspiration and expiration are generated by coupled, anatomically separate rhythm generators, one generating active expiration located close to the facial nucleus in the region of the retrotrapezoid nucleus/parafacial respiratory group, the other generating inspiration located more caudally in the preBötzinger Complex.
Janczewski
Wiktor A
WA
Department of Neurobiology, David Geffen School of Medicine, Los Angeles, CA 90095-1763, USA. victoraj@mednet.ucla.edu
Feldman
Jack L
JL
D000375:Aging; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D003655:Decerebrate State; D045853:Exhalation / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005283:Fentanyl / Q000494:pharmacology; D001239:Inhalation / Q000187:drug effects / Q000502:physiology*; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008636:Mesencephalon / Q000502:physiology* / Q000601:surgery; D009046:Motor Neurons / Q000502:physiology; D009270:Naloxone / Q000494:pharmacology; D010507:Periodicity; D011149:Pons / Q000502:physiology / Q000601:surgery; D051381:Rats; D017207:Rats, Sprague-Dawley; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000502:physiology; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
D009270:Naloxone; D005283:Fentanyl