Toxic influence of high oxygen concentration on pulmonary function and structures has been known for many years. However, the influence of high oxygen concentration breathing on defensive respiratory reflexes is still not clear. In our previous experiments, we found an inhibitory effect of 100 % oxygen breathing on cough reflex intensity in healthy guinea pigs. The present study was designed to detect the effects of hyperoxia on cough reflex in guinea pigs with allergic airway inflammation. In the first phase of our experiment, the animals were sensitized with ovalbumin. Thirty-two sensitized animals were used in two separate experiments according to oxygen concentration breathing: 100 % or 50 % oxygen for 60 h continuously. In each experiment, one group of animals was exposed to hyperoxia, another to ambient air. The cough reflex was induced both by aerosol of citric acid before sensitization, then in sensitized animals at 24 h and 60 h of exposition to oxygen/air in awake animals, and by mechanical stimulation of airway mucosa in anesthetized animals just after the end of the experiment. In contrast to 50 % oxygen, 100 % oxygen breathing leads to significant decrease in chemically induced cough in guinea pigs with allergic inflammation. No significant changes were present in cough induced by mechanical stimulation of airways., M. Brozmanová, J. Hanáček, M. Tatár, A. Strapková, P. Szépe., and Obsahuje bibliografii
Although nitrated proteins have been repeatedly used as markers of lung injury, little is known about their formation and metabolism under hyperoxia. We therefore measured 3-nitrotyrosine (3NTYR) concentrations in lung tissue and serum of rats with carrageenan-induced pneumonia exposed to hyperoxia. Twenty-nine Wistar male rats were assigned to one of 4 groups. Two experimental groups were treated by intratracheal application of carrageenan (0.5 ml of 0.7 % solution) and then one was exposed to hyperoxia for 7 days (FIO2 0.8), the other to air. Rats of two control groups breathed either hyperoxic gas mixture or air for 7 days. At the end of exposure the ventilation was determined in anesthetized, intubated animals in which 3NTYR concentrations were measured in the lung tissue and nitrites and nitrates (NOx) were estimated in the serum. Carrageenan instillation increased 3NTYR concentrations in lung tissue (carrageenan-normoxic group 147±7 pmol/g protein, control 90±10 pmol/g protein) and NOx concentration in the serum (carrageenan-normoxic group 126±13 ppb, control 78±9 ppb). Hyperoxia had no effect on lung tissue 3NTYR concentration in controls (control-hyperoxic 100±14 pmol/g protein) but blocked the increase of lung tissue 3NTYR in carrageenan-treated rats (carrageenan-hyperoxic 82±13 pmol/g protein), increased NOx in serum (control-hyperoxic 127±19 ppb) and decreased serum concentration of 3NTYR in both hyperoxic groups (carrageenan-hyperoxic 51±5 pmol/g protein, control-hyperoxic 67±7 pmol/g protein, carrageenan-normoxic 82±9 pmol/g protein, control 91±7 pmol/g protein). The results suggest that hyperoxia affects nitration of tyrosine residues, probably by increasing 3NTYR degradation.