Document Detail


Discontinuous gas exchange in the Pseudoscorpion Garypus californicus is regulated by hypoxia, not hypercapnia.
MedLine Citation:
PMID:  12324890     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The discontinuous gas exchange cycle (DGC) of the pseudoscorpion Garypus californicus is characterized by periodic bursts of CO(2) emission and by high rates of interburst CO(2) emission. We investigated the mechanism that triggers the burst phase by manipulating ambient oxygen partial pressures (Po(2)). The ventilatory trigger in most land animals is hypercapnia; in insects, for example, the burst phase is triggered when endotracheal Pco(2) reaches about 4 kPa. In insects with a DGC, hypoxia induces prolonged interburst phases because spiracular conductance is elevated to supply oxygen to the tissues, thus delaying the onset of the hypercapnia-triggered burst phase because CO(2) accumulates more slowly. In G. californicus, hypoxia induced a decrease in interburst phase length, while hyperoxia increased its duration relative to normoxia. This is opposite to the condition in insects. In addition, CO(2) emission fell during the interburst phase as ambient Po(2) rose, also opposite to the condition in insects. Thus, the burst phase is triggered in G. californicus (and presumably in other pseudoscorpions) not by hypercapnia but by hypoxia, a situation that is seldom encountered in terrestrial animals.
Authors:
John R B Lighton; Barbara Joos
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Physiological and biochemical zoology : PBZ     Volume:  75     ISSN:  1522-2152     ISO Abbreviation:  Physiol. Biochem. Zool.     Publication Date:    2002 Jul-Aug
Date Detail:
Created Date:  2002-09-26     Completed Date:  2003-01-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  100883369     Medline TA:  Physiol Biochem Zool     Country:  United States    
Other Details:
Languages:  eng     Pagination:  345-9     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, University of Nevada at Las Vegas, 4505 Maryland Parkway, 89154-4004, USA. jrlighton@aol.com
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MeSH Terms
Descriptor/Qualifier:
Animals
Anoxia / physiopathology*
Arachnida / metabolism,  physiology*
Carbon Dioxide / metabolism
Hypercapnia / physiopathology*
Oxygen / metabolism
Respiratory Physiological Phenomena*
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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