Heart rate and blood pressure variability effects as a result of oxygen and nitrous oxide administration in the anesthetized mouse

This study examines the effects of changing oxygen fractional inspiration ratio (FiO₂), and nitrous oxide (N₂O) for the improvement of cardiovascular control of mean arterial blood pressure (MAP) and heart rate (HR) in C57BL/6 mice under isoflurane anesthesia (1.5%) for up to 90 minutes post-induction. Heart rate variability (HRV) indices are also quantified under these conditions. The results indicate that changing the FiO₂ does result in lower MAP and HR values compared to the case of N₂O (50%) administration to the isoflurane gas mixture. HRV indices declined over the course of all anesthetic regimens, suggesting a decrease in parasympathetic tone. We conclude that the most optimal anesthetic condition is achieved when N₂O (50%) is added to the gas mixture.