Document Detail

Increased cardiovascular and metabolic tolerance to acute hypoxia in the rat with increased hemoglobin-O(2) affinity induced by Na-cyanate treatment.
MedLine Citation:
PMID:  10529486     Owner:  NLM     Status:  MEDLINE    
Cyanate derivatives such as NaOCN have been known to increase the hypoxia tolerance of animals by increasing the affinity of hemoglobin (Hb) to O(2). To clarify the mechanism of this increase in hypoxia tolerance, we examined changes in metabolic rate and cardiovascular parameters during a hypoxia test in halothane-anesthetized, NaOCN-treated and spontaneously breathing rats (50 mg/kg/d S.C., 10 d). Control animals received saline. The capillary density in the skeletal muscle (sternocleidomastoid muscle), cardiac papillary muscle and medulla oblongata was also examined histologically. The Hb-O(2) affinity index, P(50), decreased from 38 (control rat) to 24 mmHg in NaOCN-treated rats. During hyperoxic gas breathing, the rat treated with NaOCN showed a significantly lower metabolic rate (V(.)O(2), V(.)CO(2)), higher cardiac stroke volume, slower heart rate, lower PvO(2), and lower O(2) extraction ratio than those in control rats. The NaOCN-treated rats exhibited well-maintained arterial blood pressure and a larger cardiac output response to reduction in FIO(2) to 0.10-0.08. The increase in O(2) extraction ratio with reduction in FIO(2) was larger in NaOCN-treated than in control rats. The circulatory and metabolic depressions at FIO(2) 0.05 were effectively attenuated in NaOCN-treated rats. The capillary density of the cardiac muscle and medulla oblongata but not the skeletal muscle was significantly higher in NaOCN-treated rats than in control rats. The greater hypoxia tolerance in NaOCN-treated rats is ascribed to the combined effects of left shift of Hb-O(2) dissociation curve, lower basal V(. )O(2), higher capillary density in the heart, and brain, and other adaptive mechanisms induced probably by prolonged tissue hypoxia.
J i Taki; Y Masuda; F Hayashi; Y Fukuda
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Japanese journal of physiology     Volume:  49     ISSN:  0021-521X     ISO Abbreviation:  Jpn. J. Physiol.     Publication Date:  1999 Jun 
Date Detail:
Created Date:  2000-01-19     Completed Date:  2000-01-19     Revised Date:  2007-03-21    
Medline Journal Info:
Nlm Unique ID:  2985184R     Medline TA:  Jpn J Physiol     Country:  JAPAN    
Other Details:
Languages:  eng     Pagination:  257-65     Citation Subset:  IM    
Department of Internal Medicine III, School of Medicine, Chiba University, Chuo-ku, Chiba, 260-8670, Japan.
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MeSH Terms
Acute Disease
Anoxia / metabolism*,  physiopathology
Cardiovascular System / metabolism*,  physiopathology*
Cyanates / pharmacology*
Hemoglobins / metabolism*
Oxygen / metabolism*
Rats, Wistar
Reg. No./Substance:
0/Cyanates; 0/Hemoglobins; 7782-44-7/Oxygen; 917-61-3/sodium cyanate

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