Document Detail

Effects of nitrogen and helium on CNS oxygen toxicity in the rat.
MedLine Citation:
PMID:  15322063     Owner:  NLM     Status:  MEDLINE    
The contribution of inert gases to the risk of central nervous system (CNS) oxygen toxicity is a matter of controversy. Therefore, diving regulations apply strict rules regarding permissible oxygen pressures (Po(2)). We studied the effects of nitrogen and helium (0, 15, 25, 40, 50, and 60%) and different levels of Po(2) (507, 557, 608, and 658 kPa) on the latency to the first electrical discharge (FED) in the EEG in rats, with repeated measurements in each animal. Latency as a function of the nitrogen pressure was not homogeneous for each rat. The prolongation of latency observed in some rats at certain nitrogen pressures, mostly in the range 100 to 500 kPa, was superimposed on the general trend for a reduction in latency as nitrogen pressure increased. This pattern was an individual trait. In contrast with nitrogen, no prolongation of latency to CNS oxygen toxicity was observed with helium, where an increase in helium pressure caused a reduction in latency. This bimodal response and the variation in the response between rats, together with a possible effect of ambient temperature on metabolic rate, may explain the conflicting findings reported in the literature. The difference between the two inert gases may be related to the difference in the narcotic effect of nitrogen. Proof through further research of a correlation between individual sensitivity to nitrogen narcosis and protection by N(2) against CNS oxygen toxicity in rat may lead to a personal O(2) limit in mixed-gas diving based on the diver sensitivity to N(2) narcosis.
R Arieli; O Ertracht; I Oster; A Vitenstein; Y Adir
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-08-20
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  98     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2005 Jan 
Date Detail:
Created Date:  2004-12-13     Completed Date:  2005-05-11     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  144-50     Citation Subset:  IM    
Israel Naval Medical Institute, Israel Defense Forces Medical Corps, POB 8040, Haifa 31080, Israel.
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MeSH Terms
Administration, Inhalation
Brain / drug effects*,  physiopathology*
Dose-Response Relationship, Drug
Drug Combinations
Electromyography / methods
Evoked Potentials / drug effects
Helium / administration & dosage,  adverse effects*
Hyperbaric Oxygenation / adverse effects*
Inert Gas Narcosis / physiopathology*
Nitrogen / administration & dosage,  adverse effects*
Oxygen / administration & dosage,  adverse effects*
Rats, Sprague-Dawley
Reg. No./Substance:
0/Drug Combinations; 7440-59-7/Helium; 7727-37-9/Nitrogen; 7782-44-7/Oxygen

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