Normobaric
oxygen (NBO) and hyperbaric
oxygen (HBO) are emerging as a possible co-treatment of
acute ischemic stroke. Both have been shown to reduce
infarct volume, to improve neurologic outcome, to promote endogenous
tissue plasminogen activator-induced thrombolysis and cerebral blood flow, and to improve tissue oxygenation through
oxygen diffusion in the ischemic areas, thereby questioning the interest of HBO compared to NBO. In the present study, in order to investigate and compare the
oxygen diffusion effects of NBO and HBO on
acute ischemic stroke independently of their effects at the vascular level, we used acute brain slices exposed to
oxygen and
glucose deprivation, an ex vivo model of
brain ischemia that allows investigating the acute effects of NBO (partial pressure of
oxygen (pO2) = 1 atmospheres absolute (ATA) = 0.1 MPa) and HBO (pO2 = 2.5 ATA = 0.25 MPa) through tissue oxygenation on
ischemia-induced cell injury as measured by the release of
lactate dehydrogenase. We found that HBO, but not NBO, reduced
oxygen and
glucose deprivation-induced cell injury, indicating that passive tissue oxygenation (i.e. without vascular support) of the brain parenchyma requires
oxygen partial pressure higher than 1 ATA.