Fig 2. Stability of HBOC-based perfusate at different temperatures and its impact on mitochondrial function at hypothermic temperatures.

Panel A shows on the left-hand graph that haemoglobin levels were stable during the D-HOPE phase, and after rewarming, they were similar to the HOPE+NMP group that received fresh HBOC-based perfusate. Methaemoglobin levels (middle graph) were stable during D-HOPE and increased slowly during the rewarming, reaching comparable levels to the HOPE+NMP group during the normothermic phase. Despite the increase in the levels of methaemoglobin, arterial oxygen saturation was constant throughout the perfusion. Panel B compares markers of mitochondrial respiration between the study groups. Both groups presented a downward trend in oxygen requirements (oxygen uptake—HOPE+NMP group and oxygen consumption—cold-to-warm group), with a similar drop in the release of carbon dioxide (CO₂) in the perfusate. Reflecting an efficient mitochondrial oxidative function, both groups replenished adenosine trisphosphate (ATP) stores during the hypothermic phase. In the graphs, dots represent individual organs at the time points, and the line is the median of the values for each group. For the bar graph, the median and interquartile range are represented.