Widespread sites of brain stem ventilatory chemoreceptors
| Autor: | Eugene E. Nattie, Aihua Li, E. L. Coates |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
medicine.medical_specialty
Chemoreceptor Microinjections Physiology Central nervous system Blood Pressure Vagotomy Tissue acidosis Physiology (medical) Internal medicine medicine Animals Electrodes Phrenic nerve Acidosis Medulla Oblongata Sulfonamides business.industry Respiration Hydrogen-Ion Concentration Chemoreceptor Cells Rats Acetazolamide Phrenic Nerve Electrophysiology medicine.anatomical_structure Endocrinology Anesthesia Cats Locus Coeruleus Respiratory control medicine.symptom Extracellular Space business Brain Stem medicine.drug |
| Zdroj: | Journal of Applied Physiology. 75:5-14 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/jappl.1993.75.1.5 |
| Popis: | We produced local tissue acidosis in various brain stem regions with 1-nl injections of acetazolamide (AZ) to locate the sites of central chemoreception. To determine whether the local acidosis resulted in a stimulation of breathing, we performed the experiment in chloralose-urethan anesthetized vagotomized carotid-denervated (cats) paralyzed servo-ventilated cats and rats and measured phrenic nerve activity (PNA) as the response index. Measurements of extracellular brain tissue pH by glass microelectrodes showed that AZ injections induced a change in pH at the injection center equivalent to that produced by an increase in end-tidal PCO2 of approximately 36 Torr and that the change in brain pH was limited to a tissue volume with a radius of < 350 microns. We found AZ injections sites that caused a significant increase in PNA to be located 1) within 800 microns of the ventrolateral medullary surface at locations within traditional rostral and caudal chemosensitive areas and the intermediate area, 2) within the vicinity of the nucleus tractus solitarii, and 3) within the vicinity of the locus coeruleus. Single AZ injections produced increases in PNA that were < or = 69% of the maximum value observed with an increase in end-tidal PCO2. We conclude that central chemoreceptors are distributed at many locations within the brain stem, all within 1.5 mm of the surface, and that stimulation of a small fraction of all central chemoreceptors can result in a large ventilatory response. |
| Databáze: | OpenAIRE |
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