Study objectives: To implement a chronic rat model of recurrent airway obstructions to study the obstructive sleep apnea (OSA) syndrome.
Design: Prospective controlled animal study.
Setting: University laboratory.
Patients or participants: 24 male Sprague-Dawley rats (250-300 g).
Interventions: The rats were placed in a setup consisting of a body chamber and a head chamber separated by a neck collar specially designed to apply recurrent airway obstructions with OSA patterns. Rats in the Obstruction group (n=8) were subjected to 5-s obstructions at a rate of 60 per hour, 6 h/day during 4 weeks. Sham rats (n=8) were placed in the setup but no obstructions were applied. Naive rats (n=8) were subjected to no intervention.
Measurements and results: Breathing flow, pressure, CO2 air concentration, and SpO2 showed that the model mimicked OSA respiratory events (obstructive apneas, increased respiratory efforts, and oxygen saturation dips). Animal stress, assessed by body weight and plasma corticosterone, was not significantly different across Obstruction and Sham groups. This supports the concept that this novel model does not introduce a significant burden of stress in the rat after acclimatization to the chamber. Thromboxane-B2/6-keto-Prostaglandin-Flalpha ratio in plasma, which is an index of vasoconstriction, was significantly increased in the rats subjected to obstructions.
Conclusions: The designed animal model of chronic recurrent airway obstructions is feasible and potentially useful to study the mechanisms involved in the cardiovascular consequences of OSA.