Optimized open-source setting for subjecting rodents to chronic normobaric hypoxia in facilities with minimal nitrogen supply

Otero J, Rodríguez-Lázaro MA, Salama R, Mbanze D, Solana G, Muñoz-Vaño V, Cámara Y, Almendros I, Farré R.

Under review

 

ABSTRACT:

Background: Very prevalent respiratory and cardiovascular diseases result in chronic hypoxia, promoting metabolic, kidney, heart, and other malignant diseases. Hypoxia research employs animal models based on chronically breathing hypoxic air (O2<21%), usually by injecting N2 into
the animal’s chamber. However, continuous high-flow N2 supply is available only in limited facilities, reducing the capability of widely conducting hypoxia research. Aim: Here, we describe an optimized setting for subjecting rodents to chronic normobaric hypoxia by requiring minimal N2 supply. Methods: The setting is based on providing the O2 consumed by the animals and eliminating the exhaled CO2 and water vapor. O2, CO2, temperature, and humidity in the hypoxic chamber are controlled by an Arduino-based unit activating a pump that introduces room air to restore the metabolized O2. Another pump continuously recirculates the chamber air through a Peltier-based drier and CO2-absorbing soda lime. To correct any deviation in the actual value of hypoxia within the chamber, the control unit allows the injection of N2 into the chamber from a gas source. Results: The setting performance was successfully tested in vivo when subjecting mice to 11%-O2 chronic hypoxia. Conclusion: This device, requiring a low N2 supply, may facilitate in vivo experimental research of hypoxia related diseases.