Medullary effects of nicotine and GABA on tracheal smooth muscle tone
| Autor: | E. Chandler Deal, Neil S. Cherniack, Erik van Lunteren, Matthew P. Norcia, Musa A. Haxhui, Jyoti Mitra |
|---|---|
| Rok vydání: | 1986 |
| Předmět: |
Pulmonary and Respiratory Medicine
Male medicine.medical_specialty Nicotine Physiology Administration Topical Hexamethonium Compounds Bicuculline Hexamethonium gamma-Aminobutyric acid GABA Antagonists chemistry.chemical_compound Internal medicine Medicine Animals gamma-Aminobutyric Acid Phrenic nerve Medulla Oblongata Central chemoreceptors business.industry Airway Resistance Lidocaine respiratory system GABA receptor antagonist Carbon Dioxide Phrenic Nerve Trachea Endocrinology chemistry Anesthesia Cats GABAergic Female business medicine.drug |
| Zdroj: | Respiration physiology. 64(3) |
| ISSN: | 0034-5687 |
| Popis: | Airway tone can be modulated centrally by the brain as well as by peripheral receptors. In part these changes in airway caliber seem to be secondary to changes in respiratory activity. Since structures near the ventrolateral medullary surface (VMS) can produce profound effects on respiration, it seems reasonable to believe that they might also be capable of modifying tracheal tone. In this study we examined the effects of two agents with respect to their action on tracheal tone; nicotine, a respiratory stimulant when applied to VMS, and gamma aminobutyric acid (GABA), a respiratory depressant when similarly administered. In chloralose anesthetized, paralyzed, artificially ventilated cats, tracheal tone was assessed by measuring pressure changes in a rostral bypassed of the trachea, while phrenic nerve activity was examined simultaneously. Nicotine administered on the intermediate area of the VMS both before and after carotid sinus denervation increased phrenic activity and induced constriction of the rostral tracheal segment. The response to nicotine could be blocked by application of a nicotine antagonist, hexamethonium, or prior local administration of lidocaine to the VMS. Activation of GABAergic receptors by application of GABA on the intermediate area of the VMS markedly reduced respiratory activity and nearly abolished the increased tracheal tone produced by inhalation of 7% CO 2 in O 2 . The effects of GABA were eliminated by the prior administration to the VMS of bicuculline, a GABA receptor antagonist. These results indicate that structures located on the ventral surface of the medulla which affect breating may also play a significant role in the regulation of airway smooth muscle tone. |
| Databáze: | OpenAIRE |
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