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by Keyword: Obstructive apnea


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Dalmases, M., Torres, M., Márquez-Kisinousky, L., Almendros, I., Planas, A. M., Embid, C., Martínez-Garcia, M. A., Navajas, D., Farré, R., Montserrat, J. M., (2014). Brain tissue hypoxia and oxidative stress induced by obstructive apneas is different in young and aged rats Sleep , 37, (7), 1249-1256

Study Objectives: To test the hypotheses that brain oxygen partial pressure (PtO2) in response to obstructive apneas changes with age and that it might lead to different levels of cerebral tissue oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: Sixty-four male Wistar rats: 32 young (3 mo old) and 32 aged (18 mo). Interventions: Protocol 1: Twenty-four animals were subjected to obstructive apneas (50 apneas/h, lasting 15 sec each) or to sham procedure for 50 min. Protocol 2: Forty rats were subjected to obstructive apneas or sham procedure for 4 h. Measurements and Results: Protocol 1: Real-time PtO2 measurements were performed using a fast-response oxygen microelectrode. During successive apneas cerebral cortex PtO2 presented a different pattern in the two age groups; there was a fast increase in young rats, whereas it remained without significant changes between the beginning and the end of the protocol in the aged group. Protocol 2: Brain oxidative stress assessed by lipid peroxidation increased after apneas in young rats (1.34 ± 0.17 nmol/mg of protein) compared to old ones (0.63 ± 0.03 nmol/mg), where a higher expression of antioxidant enzymes was observed. Conclusions: The results suggest that brain oxidative stress in aged rats is lower than in young rats in response to recurrent apneas, mimicking obstructive sleep apnea. This could be due to the different PtO2 response observed between age groups and the increased antioxidant expression in aged rats.

Keywords: Aging, Animal model, Obstructive apnea, Oxidative stress, Tissue oxygenation, antioxidant, glutathione disulfide, aged, animal experiment, animal model, animal tissue, apnea, arterial oxygen saturation, article, brain cortex, brain oxygen tension, brain tissue, controlled study, groups by age, hypoxia, lipid peroxidation, male, nonhuman, oxidative stress, pressure, priority journal, rat


Almendros, Isaac, Farre, Ramon, Planas, Anna M., Torres, Marta, Bonsignore, Maria R., Navajas, Daniel, Montserrat, Josep M., (2011). Tissue oxygenation in brain, muscle, and fat in a rat model of sleep apnea: Differential effect of obstructive apneas and intermittent hypoxia Sleep , 34, (8), 1127-1133

Study Objectives: To test the hypotheses that the dynamic changes in brain oxygen partial pressure (PtO(2)) in response to obstructive apneas or to intermittent hypoxia differ from those in other organs and that the changes in brain PtO(2) in response to obstructive apneas is a source of oxidative stress. Design: Prospective controlled animal study. Setting: University laboratory. Participants: 98 Sprague-Dawley rats. Interventions: Cerebral cortex, skeletal muscle, or visceral fat tissues were exposed in anesthetized animals subjected to either obstructive apneas or intermittent hypoxia (apneic and hypoxic events of 15 s each and 60 events/h) for 1 h. Measurements and Results: Arterial oxygen saturation (spO(2)) presented a stable pattern, with similar desaturations during both stimuli. The PtO(2) was measured by a microelectrode. During obstructive apneas, a fast increase in cerebral PtO(2) was observed (38.2 +/- 3.4 vs. 54.8 +/- 5.9 mm Hg) but not in the rest of tissues. This particular cerebral response was not found during intermittent hypoxia. The cerebral content of reduced glutathione was decreased after obstructive apneas (46.2% +/- 15.2%) compared to controls (100.0% +/- 14.7%), but not after intermittent hypoxia. This antioxidant consumption after obstructive apneas was accompanied by increased cerebral lipid peroxidation under this condition. No changes were observed for these markers in the other tissues. Conclusions: These results suggest the cerebral cortex could be protected in some way from hypoxic periods caused by obstructive apneas. The increased cerebral PtO(2) during obstructive apneas may, however, cause harmful effects (oxidative stress). The obstructive apnea model appears to be more adequate than the intermittent hypoxia model for studying brain changes associated with OSA.

Keywords: Tissue oxygenation, Obstructive apnea, Intermittent hypoxia, Animal model, Oxidative stress