Effects of Long Term High Oxygen Concentration Breathing on Defensive Respiratory Reflexes in Guinea-pigs
✍ Scribed by Jan Hanacek; Mariana Brozmanova; Milos Tatar; Danka Karcolova; Anna Strapkova; Peter Szepe
- Publisher
- Elsevier
- Year
- 1996
- Tongue
- English
- Weight
- 210 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0952-0600
No coin nor oath required. For personal study only.
✦ Synopsis
Introduction
reflex was induced by citric acid aerosol (CA 0.3mol/ l; mass median diameter 1.2 m) delivered to the head The lung injury induced by high concentrations of part of the plethysmograph box (type 855 H. Sachs oxygen in men and experimental animals has been Elektronik) during 2 min (in awake animals). An known for years. 1,2 The sequence of histological aerosol of CA was prepared by jet nebulizer (Parichanges that occurs in the lungs in response to hyprovocation test I, Menzel). peroxia are known and seems to be quite similar on Cough was provoked before exposure, then 24h, different animal species, 1 and in humans. 3 However, 48h and 60h after exposure began. The number of pathophysiological responses of the respiratory system coughs was counted during inhalation of CA and to hyperoxia are incompletely known. We are parduring 1 min immediately after, from the airflow trace. ticularly ignorant of the influence of hyperoxia in Just after the end of the exposure the animals were defensive respiratory reflexes. According to data on anesthetized (urethane, 1g/kg, ip), and cough and morphological and functional changes induced by sneezing were induced by mechanical stimulation long-term hyperoxia in airways mucosa we suppose (silon fibre-0.3mm diameter) of the nasal, laryngothat reflexive defensive mechanisms of the respiratory pharyngeal (LPh) and tracheobronchial (TBr) mutract would be influenced by exposure to high concosa, respectively. The numbers of coughs and sneezes centrations of oxygen.
were counted during the stimulation period (5s). Re-This study was designed to test our supposition.
flexes were detected as transient changes of interpleural pressure recorded by multiscriptor.
Methods
The concentration of oxygen was measured by Permolyt 3 (VEB Junkalor), and CO 2 concentration Adult female Trik guinea-pigs (n=56) weighting was measured by Capnograph MKII (Gould Godard). 230-340g were used in three separate experiments. In the first of them 8 animals were exposed to pure Statistical analysis normobaric oxygen (PNO) for 48h. The second experiment was performed on 8 animals exposed to
The numbers of coughs/sneezes are expressed as median PNO for 60h. Twelve animals were exposed to 50% and interquartil range. Mann-Whitney U test and Wiloxygen for 60h. In each experiment the control group coxon Signed Rank test were used to compare numbers of animals was used and was exposed to room air.
of coughs/sneezes between animals exposed to room air Exposure of animals to oxygen or room air was and to high concentrations of oxygen at respective times. performed in glass metabolic cages individually and P value <0.05 was considered significant. continuously. Parameters of the cage environment were maintained at the following level: humidity 55-70%, temperature 23-25°C; concentration of O 2 >95% RESULTS (in first and second experiment), 50% (in third ex-Citric acid cough periment), concentration of CO 2 >0.2%.
Oxygen was delivered from cylinders of pure oxy-The number of coughs in animals exposed to PNO gen, and room air by pump. We recorded two parafor 24h and 48h was not changed significantly but a meters: airflow in the thoracic part of the tendency to its inhibition was present. A significant plethysmograph box (in awake animals), and interpleural pressure (in anesthetized ones). The cough decline of cough numbers was present in animals