Effect of systemic hypoxia and reoxygenation on electrical stability of the rat myocardium: chronophysiological study

Title:

Effect of systemic hypoxia and reoxygenation on electrical stability of the rat myocardium: chronophysiological study

Creator:

Švorc, P., Beňačka, R., Petrášová, D., Bračoková, I., and Kujaník, Š.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:273cae22-3235-4ec4-b0d0-998d7165f578
uuid:273cae22-3235-4ec4-b0d0-998d7165f578

Subject:

Electrical stability of the heart, LD cycle, Hypoventilation, and Rat

Type:

article, model:article, and TEXT

Description:

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 VT = 1 ml/100 g, respiratory rate 40 breaths/min, hypoventilation VT = 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.

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Physiological research | 2005 Volume:54 | Number:3

Harvested from:

CDK

Metadata only:

false