Biomaterial Database

The carotid chemoreceptor input to the respiratory neurones of the nucleus of tractus solitarus. 1977

J Lipski, and R M McAllen, and K M Spyer

1. An investigation has been made into the connexions between the carotid body chemoreceptors and the dorsal respiratory neurones of the cat's medulla.2. In confirmation of previous work these neurones were found to be all inspiratory in firing pattern and to fall into two categories, Ralpha (forty-four units) which fire only with the central inspiratory rhythm and Rbeta (thirty-two neurones) that are also excited by lung inflation. Both categories were shown to be excited by stimuli delivered to the carotid bodies during inspiration but, with a single exception, not during expiration.3. When Rbeta neurones were made to fire tonically in expiration by maintained lung inflation, chemoreceptor activation inhibited this discharge in 7/11 cases, the remainder being unaffected.4. Iontophoretically applied DL-homocysteic acid or glutamate made both Ralpha and Rbeta neurones fire tonically in expiration. Chemoreceptor stimulation during expiration inhibited this activity in all neurones tested (nine Ralpha and three Rbeta cells).5. Using the measurement of the antidromic latency to spinal stimulation as an index of membrane potential, evidence was obtained that any subthreshold influence of the chemoreceptors on dorsal respiratory neurones during expiration was inhibitory (9/18 cases).6. It is concluded that chemoreceptors do not even subliminally excite dorsal inspiratory neurones during expiration; such influence as they have then is inhibitory. Possible reasons for this difference in chemoreceptor influence during inspiration and expiration are discussed. It is suggested that chemoreceptor excitation reaches them only as part of an enhanced central inspiratory drive from an as yet unknown source.

UI	MeSH Term	Description	Entries
D008526	Medulla Oblongata	The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.	Accessory Cuneate Nucleus,Ambiguous Nucleus,Arcuate Nucleus of the Medulla,Arcuate Nucleus-1,External Cuneate Nucleus,Lateral Cuneate Nucleus,Nucleus Ambiguus,Ambiguus, Nucleus,Arcuate Nucleus 1,Arcuate Nucleus-1s,Cuneate Nucleus, Accessory,Cuneate Nucleus, External,Cuneate Nucleus, Lateral,Medulla Oblongatas,Nucleus, Accessory Cuneate,Nucleus, Ambiguous,Nucleus, External Cuneate,Nucleus, Lateral Cuneate
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
D009433	Neural Inhibition	The function of opposing or restraining the excitation of neurons or their target excitable cells.	Inhibition, Neural
D009434	Neural Pathways	Neural tracts connecting one part of the nervous system with another.	Neural Interconnections,Interconnection, Neural,Interconnections, Neural,Neural Interconnection,Neural Pathway,Pathway, Neural,Pathways, Neural
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D002344	Carotid Body	A small cluster of chemoreceptive and supporting cells located near the bifurcation of the internal carotid artery. The carotid body, which is richly supplied with fenestrated capillaries, senses the pH, carbon dioxide, and oxygen concentrations in the blood and plays a crucial role in their homeostatic control.	Glomus Caroticum,Bodies, Carotid,Body, Carotid,Caroticum, Glomus,Carotid Bodies
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003544	Cysteic Acid	Beta-Sulfoalanine. An amino acid with a C-terminal sulfonic acid group which has been isolated from human hair oxidized with permanganate. It occurs normally in the outer part of the sheep's fleece, where the wool is exposed to light and weather.	3-Sulfoalanine,beta-Sulfoalanine,Cysteate,3 Sulfoalanine,Acid, Cysteic,beta Sulfoalanine
D005971	Glutamates	Derivatives of GLUTAMIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure.	Glutamic Acid Derivatives,Glutamic Acids,Glutaminic Acids