US EPA

7093515 

Journal Article 

Effects of vagotomy on cardiovascular and heart rate variability alterations following chronic normobaric hypoxia in adult rabbits 

Alcayaga, J; Del Rio, R; Moya, EA; Freire, M; Iturriaga, R; , 

2018 

Yes 

Biological Research
ISSN: 0716-9760
EISSN: 0717-6287 

SOC BIOLGIA CHILE 

SANTIAGO 

51 

1 

57 

English 

30572940 

10.1186/s40659-018-0207-2 

WOS:000453897600001 

Background: chronic hypoxia increases basal ventilation and pulmonary vascular resistance, with variable changes in arterial blood pressure and heart rate, but it's impact on heart rate variability and autonomic regulation have been less well examined. We studied changes in arterial blood pressure, heart rate and heart rate variability (HRV) in rabbits subjected to chronic normobaric hypoxia (CNH; PB similar to 719 mmHg;-FIO2 similar to 9.2%) for 14 days and assess the effect of autonomic control by acute bilateral vagal denervation.Results: exposure to CNH stalled animal weight gain and increased the hematocrit, without affecting heart rate or arterial blood pressure. Nevertheless, Poincare plots of the electrocardiographic R-R intervals showed a reduced distribution parallel to the line of identity, which interpreted as reduced long-term HRV. In the frequency domain, CNH reduced the very-low-(< 0.2 Hz) and high-frequency components (> 0.8 Hz) of the R-R spectrograms and produced a prominent component in the low-frequency component (0.2-0.5 Hz) of the power spectrum. In control and CNH exposed rabbits, bilateral vagotomy had no apparent effect on the short-and long-term HRV in the Poincare plots. However, bilateral vagotomy differentially affected higher-frequency components (> 0.8 Hz); reducing it in control animals without modifying it in CNH-exposed rabbits.Conclusions: These results suggest that CNH exposure shifts the autonomic balance of heart rate towards a sympathetic predominance without modifying resting heart rate or arterial blood pressure.