Naloxone application to the ventrolateral medulla enhances the respiratory response to inspired carbon dioxide

Previous studies have shown that systemic administration of the opiate antagonist naloxone potentiates the ventilatory response to inspired carbon dioxide. The present study was designed to localize the site of action of naloxone for increasing the respiratory chemosensitivity to inhaled carbon diox...

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Bibliographic Details
Published inLife sciences (1973) Vol. 49; no. 3; p. 193
Main Authors Trouth, C O, Bada, F J, Pan, Y, Holloway, J A, Millis, R M, Bernard, D G
Format Journal Article
LanguageEnglish
Published Netherlands 1991
Subjects
Animals
Carbon Dioxide - pharmacology
Cats
Chemoreceptor Cells - drug effects
Electrophysiology
Female
Male
Medulla Oblongata - drug effects
Medulla Oblongata - physiology
Naloxone - pharmacology
Respiration - drug effects
Respiratory Function Tests
Stimulation, Chemical
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Summary:Previous studies have shown that systemic administration of the opiate antagonist naloxone potentiates the ventilatory response to inspired carbon dioxide. The present study was designed to localize the site of action of naloxone for increasing the respiratory chemosensitivity to inhaled carbon dioxide (CO2) in cats. Naloxone applied topically to the caudal chemosensitive area on the ventral medullary surface (VMS) during hypercapnic breathing produced a 75% greater increase in minute ventilation than hypercapnic breathing alone. Furthermore, hypercapnic breathing produced a 200% increase in neuronal activity of VMS chemosensitive cells; this was further increased 120% by naloxone. It is concluded that naloxone increases the sensitivity of neurons in the caudal respiratory chemosensitive area of cats to hypercapnia, and that endogenous opiates may act as modulators at VMS chemosensitive sites during hypercapnic breathing.
ISSN:0024-3205
DOI:10.1016/0024-3205(91)90003-T