Frequency responses to hypoxia and hypercapnia in carotid body-denervated conscious rats

The ventilatory response to brief, severe hypoxia is biphasic consisting of an initial facilitation followed by a slowing of breathing frequency ( f r). After the hypoxic stimulus is removed, f r drops below baseline levels. This phenomenon is called the post-hypoxic frequency decline ( phfd). These...

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Bibliographic Details
Published in:Respiratory physiology & neurobiology 2002-04, Vol.130 (2), p.113-120
Main Authors: Coles, Sharon K., Miller, Rob, Huela, Julie, Wolken, Patty, Schlenker, Evelyn
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cardiorespiratory control. Arterial mecano- and chemoreceptor
Carotid Body - injuries
Carotid Body - physiopathology
Carotid body, post-hypoxic frequency decline
Carotid Sinus - innervation
Control of breathing, hypoxic response
Denervation
Fundamental and applied biological sciences. Psychology
Hypercapnia - physiopathology
Hypoxia - physiopathology
Hypoxia, post-hypoxic frequency decline
Male
Mammals, rat
Pattern of breathing, hypoxic response
Plethysmography - methods
Rats
Rats, Sprague-Dawley
Reaction Time
Respiration
Time Factors
Vertebrates: respiratory system
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Summary:The ventilatory response to brief, severe hypoxia is biphasic consisting of an initial facilitation followed by a slowing of breathing frequency ( f r). After the hypoxic stimulus is removed, f r drops below baseline levels. This phenomenon is called the post-hypoxic frequency decline ( phfd). These f r changes are due to reciprocal changes in expiratory time (T e), mediated by the ventrolateral pontine A 5 region (J. Physiol. (London) 497 (1996) 79; Am. J. Physiol. 274 (1998) R1546). The purpose of this study was to determine if carotid body input is required for full manifestation of phfd by quantifying ventilation in intact and carotid sinus denervated rats in response to hypoxic, and contrasted with hypercapnic stimuli. Following carotid denervation the initial facilitation of f r was eliminated in response to hypoxia, but the phfd remained. In contrast the pattern in response to increased CO 2 remained constant before and after carotid denervation. These results suggest that phfd is not dependent upon carotid body stimulation, but is mediated centrally.
ISSN:1569-9048
1878-1519
DOI:10.1016/S0034-5687(02)00005-1