Respiratory rhythm generation in chick hindbrain: effects of MK-801 and vagotomy.
Hindbrain mechanisms generating the respiratory rhythm in chicks were analysed. In vivo, ventilation and intercostal muscle activity were recorded in chicks (1 and 2.5 weeks-old), vagotomized and treated with the NMDA receptor blocker MK-801 (dizocilpine). In vitro, synaptic transmission from vagal to second-order sensory neurones was studied in the nucleus of the solitary tract, using whole-cell recordings in slices. Vagal afferents were found to act through GABAergic synapses and control two hindbrain systems: a dizocilpine-sensitive control system and a rhythm generator. Although this organization is the same as in mammals, after vagotomy entirely different respiratory patterns emerge: (i) expiratory-inspiratory efforts triggered by the rhythm generator and (ii) periods of apnoea produced by the dizocilpine-sensitive system.
Fortin
G
G
Biologie Fonctionnelle du Neurone, Institut Alfred Fessard, C.N.R.S., Gif-sur-Yvette, France.
Foutz
A S
AS
Champagnat
J
J
D000818:Animals; D002645:Chickens; D003655:Decerebrate State / Q000503:physiopathology; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004576:Electromyography / Q000187:drug effects; D010991:Plethysmography; D015656:Respiratory Mechanics / Q000502:physiology*; D012249:Rhombencephalon / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D014628:Vagotomy; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005680:gamma-Aminobutyric Acid; D016291:Dizocilpine Maleate