Decreasing FIO2 induces spontaneous intermittent hypoxic events in mice

Abstract

Chronic intermittent hypoxia, CIH, is a feature of sleep apnea widely used in research to mechanistically examine the physiological effects of sleep apnea. These mechanistic studies commonly utilize mice as the study model. In room air, mice experience periodic apneas and arterial oxygen desaturations. Activation of the carotid body could stabilize breathing and decrease these events. Therefore, we hypothesized that C57BL/6J mice experience fewer hypoxic events with decreasing FIO2.We placed 6 C57BL/6J mice (3 male, 3 female) in an Emka® unrestrained barometric plethysmograph and measured pulse oximetry using the STARR LifeSciences MouseOx® Plus system. The mice were exposed to different levels of FIO2 for 10 minutes each: 0.21, 0.15, 0.12, 0.09, 0.30 ± 0.01. We defined a hypoxic event as 3% deviation from the average oxygen saturation at each FIO2. Mice did not show fewer hypoxic events when exposed to increasing levels of hypoxia. In fact, mice experienced more hypoxic events at 0.15 than 0.21 and 0.30 FIO2 (P<0.05). Mice also experienced more hypoxic events at 0.12 than at 0.30 FIO2. Additionally, we found that hypoxic event nadir SpO2 was significantly lower at all FIO2 levels when compared to 0.21 FIO2. Hypoxic events at all FIO2 levels had significantly lower average SpO2 compared to 0.21 FIO2. No change was observed for average SpO2 for hypoxic events at 0.30 FIO2 relative to 0.21 FIO2. Contrary to our hypothesis, intermittent hypoxic events are not stabilized by exposure to a hypoxic environment. Future work will evaluate this in other mouse strains. 1R56HL152365 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.