Document Detail

Effect of systemic hypoxia and reoxygenation on electrical stability of the rat myocardium: chronophysiological study.
MedLine Citation:
PMID:  15588156     Owner:  NLM     Status:  MEDLINE    
The aim of the study was to determine the dependence of changes in the electrical stability of the heart on the light-dark cycle (LD cycle) in disorders of pulmonary ventilation. The ventricular arrhythmia threshold (VAT) was measured in female Wistar rats (adaptation to the light regime 12:12 h, ketamine/xylazine anesthesia 100 mg/15 mg/kg, i.m., open chest experiments). The conditions of the normal artificial ventilation and reoxygenation were V(T) = 1 ml/100 g, respiratory rate 40 breaths/min, hypoventilation V(T) = 0.5 ml/100 g, respiratory rate 20 breaths/min. The animals (n=11 light group; n=19 dark group) were subjected to 20 min hypoventilation followed by 20 min reoxygenation. The control prehypoventilatory VAT differences were not found between the light (1.90+/-0.84 mA) and dark (1.88+/-0.87 mA) part of the day. Artificial hypoventilation changed the VAT values in light and dark part of the day differently. While during the light period, the average VAT values in most animals (90.9 %) were significantly decreased (1.29+/-0.59 vs. 1.90+/-0.84 mA control, p<0.05), during the dark part these values showed either significant increase (63.2 %) (2.23+/-0.77 vs. 1.48+/-0.39 mA, p<0.005) or a slight non-significant decrease (36.8 %) (2.18+/-0.89 vs. 2.54+/-0.99 mA). Reoxygenation returned the VAT values to the level before hypoventilation by an increase of the VAT (81.8 %) in the light part of day and by decrease of the VAT (68.4 %) in the dark part of the day. It is concluded that 1) in hypoventilation/reoxygenation model, the significant higher average VAT values are in the dark part of the day vs. the light one, 2) rat hearts are more resistant to systemic hypoxia and reoxygenation in the dark part of day, and 3) proarrhythmogenic effect of the systemic hypoxia is only seen in the light part of the day.
P Svorc; R Benacka; D Petrásová; I Bracoková; S Kujaník
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-12-09
Journal Detail:
Title:  Physiological research / Academia Scientiarum Bohemoslovaca     Volume:  54     ISSN:  0862-8408     ISO Abbreviation:  Physiol Res     Publication Date:  2005  
Date Detail:
Created Date:  2005-06-24     Completed Date:  2005-10-05     Revised Date:  2008-04-02    
Medline Journal Info:
Nlm Unique ID:  9112413     Medline TA:  Physiol Res     Country:  Czech Republic    
Other Details:
Languages:  eng     Pagination:  319-25     Citation Subset:  IM    
Department of Physiology, Department of Pathophysiology, Medical Faculty, Safarik University, Kosice, Slovak Republic.
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MeSH Terms
Anoxia / complications,  physiopathology*,  therapy*
Circadian Rhythm*
Heart Conduction System / physiopathology*
Oxygen / metabolism*
Rats, Wistar
Respiration, Artificial*
Tachycardia, Ventricular / etiology,  physiopathology*
Reg. No./Substance:

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

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