Effect of chronic hypoxia on breathing and EMGs of respiratory muscles in awake ponies.
Abstract: Breathing, diaphragmatic and transversus abdominis electromyograms (EMGdi and EMGta, respectively), and arterial blood gases were studied during normoxia (arterial PO2 = 95 Torr) and 48 h of hypoxia (arterial PO2 = 40-50 Torr) in intact (n = 11) and carotid body-denervated (CBD, n = 9) awake ponies. In intact ponies, arterial PCO2 was 7, 5, 9, and 11 Torr below control (P less than 0.01) at 1 and 10 min and 5 and 24-48 h of hypoxia, respectively. In CBD ponies, arterial PCO2 was 3-4 Torr below control (P less than 0.01) at 4, 5, 6, and 24 h of hypoxia. In intact ponies, pulmonary ventilation, mean inspiratory flow rate, and rate of rise of EMGdi and EMGta changed in a multi-phasic fashion during hypoxia; each reached a maximum during the 1st h (P less than 0.05), declined between 1 and 5 h (P less than 0.05), and increased between 5 and 24-48 h of hypoxia. As a result of the increased drive to the diaphragm, the mean EMGdi was above control throughout hypoxia (P less than 0.05). In contrast, as a result of a sustained reduction in duration of the EMGta, the mean EMGta was below control for most of the hypoxic period. In CBD ponies, pulmonary ventilation and mean inspiratory flow rate did not change during chronic hypoxia (P greater than 0.10). In these ponies, the rate of rise of the EMGdi was less than control (P less than 0.05) for most of the hypoxic period, which resulted in the mean EMGdi to also be less than control (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1992-02-01 PubMed ID: 1559954DOI: 10.1152/jappl.1992.72.2.739Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The study examines the effects of reduced oxygen supply for an extended period on the respiratory responses, respiratory muscle activity, and arterial blood gas composition in ponies. Significant alterations were observed in breathing, diaphragmatic and transversus abdominis electromyograms, and arterial blood gases during 48 hours of reduced oxygen supply.
Objective of the Research
- The study aimed to comprehend the effect of extended reduced oxygen levels (chronic hypoxia) on the process of respiration and the activity of respiratory muscles in ponies. It also sought to compare the results in two categories of ponies; intact and carotid body-denervated (CBD).
Methodology
- The subjects were divided into two groups of intact and CBD ponies, with 11 and 9 members respectively.
- Measurements involving breathing, diaphragmatic and transversus abdominis electromyograms (EMGdi and EMGta) were studied under two conditions; normal oxygen level and after 48 hours of reduced oxygen level.
- Arterial blood gases were also analyzed in the two set conditions.
Findings
- In intact ponies, a significant drop was noted in arterial PCO2 at 1&10 min and 5&24-48 hours of reduced oxygen supply.
- CBD ponies also showed a considerable decrease in arterial PCO2 at 4, 5, 6, and 24 hours of reduced oxygen supply.
- In response to reduced oxygen levels, intact ponies demonstrated a multi-phasic alteration in pulmonary ventilation, mean inspiratory flow rate, and rate of rise of EMGdi and EMGta. Notably, all measures peaked during the first hour, then decreased between 1 to 5 hours, and rose again from 5 to 24-48 hours of reduced oxygen supply.
- On the contrary, in CBD ponies, pulmonary ventilation and mean inspiratory flow rate remained unaffected during reduced oxygen supply.
- The CBD ponies demonstrated a lower rate of rise of the EMGdi during the period of reduced oxygen supply, which resulted in the mean EMGdi also being less than the control destination.
Cite This Article
APA
Brown DR, Forster HV, Lowry TF, Forster MA, Forster AL, Gutting SM, Erickson BK, Pan LG.
(1992).
Effect of chronic hypoxia on breathing and EMGs of respiratory muscles in awake ponies.
J Appl Physiol (1985), 72(2), 739-747.
https://doi.org/10.1152/jappl.1992.72.2.739 Publication
Researcher Affiliations
- Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
MeSH Terms
- Animals
- Carotid Body / physiopathology
- Central Nervous System / physiopathology
- Chemoreceptor Cells / physiopathology
- Chronic Disease
- Denervation
- Electromyography
- Horses
- Hypoxia / physiopathology
- Muscle Contraction / physiology
- Respiratory Mechanics / physiology
- Respiratory Muscles / physiopathology
Grant Funding
- HL-25739 / NHLBI NIH HHS
Citations
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