Document Detail

The ventilatory response to CO2 of the peripheral and central chemoreflex loop before and after sustained hypoxia in man.
MedLine Citation:
PMID:  1293293     Owner:  NLM     Status:  MEDLINE    
1. The ventilatory response to sustained hypoxia is characterized by a fast increase due to the peripheral chemoreceptors followed by a slow decline. The mechanism of this decline is unknown. 2. To investigate the characteristics of the ventilatory response to sustained hypoxia ten healthy subjects were exposed to two consecutive periods of isocapnic hypoxia (arterial saturation 78%) separated by a 5 min exposure to isocapnic normoxia. 3. The acute hypoxic response to the second exposure to hypoxia (mean increase in ventilation +/- S.E.M., 7.2 +/- 0.8 l min-1) was significantly depressed (P = 0.04) compared to the first one (9.5 +/- 1.3 l min-1). 4. To investigate whether this depression was due to central or peripheral effects or both we measured, in the same ten subjects, the normoxic ventilatory response to CO2 before and after a period of 25 min of hypoxia using the technique of dynamic end-tidal forcing. 5. Each response was separated into a fast peripheral and slow central component characterized by a CO2 sensitivity, time constant, time delay and an off-set. 6. A total of thirty-six prehypoxic and thirty posthypoxic responses were analysed. The ventilatory CO2 sensitivities of the peripheral and central chemoreflex loops and the overall off-set (apnoeic threshold) after 25 min of hypoxia were somewhat larger than their prehypoxic values, but this effect was not significant. 7. We argue that the hypoxic ventilatory decline in man is due to a change in the off-set of the peripheral chemoreflex loop.
A Berkenbosch; A Dahan; J DeGoede; I C Olievier
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of physiology     Volume:  456     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1992 Oct 
Date Detail:
Created Date:  1993-04-05     Completed Date:  1993-04-05     Revised Date:  2010-09-07    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  71-83     Citation Subset:  IM    
Department of Physiology, University of Leiden, The Netherlands.
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MeSH Terms
Carbon Dioxide / physiology*
Chemoreceptor Cells / physiology*
Oxygen / blood,  physiology*
Respiration / physiology*
Sensory Thresholds / physiology
Time Factors
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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