During the past decade, studies on the manipulation of various inhaled
inert gases during
ischemia and/or reperfusion have led to the conclusion that
inert gases may be promising agents for treating
acute ischemic stroke and perinatal
hypoxia-
ischemia insults. Although there is a general consensus that among these
gases xenon is a golden standard, the possible widespread clinical use of
xenon experiences major obstacles, namely its availability and cost of production. Interestingly, recent findings have shown that
helium, which is a cost-efficient inert gas with no
anesthetic properties, can provide neuroprotection against
acute ischemic stroke in vivo when administered during
ischemia and early reperfusion. We have investigated whether
helium provides neuroprotection in rats subjected to
middle cerebral artery occlusion (MCAO) when administered after reperfusion, a condition prerequisite for the therapeutic viability and possible clinical use of
helium. In this study, we show that
helium at 75 vol% produces neuroprotection and improvement of neurologic outcome in rats subjected to transient MCAO by producing
hypothermia on account of its high specific heat as compared with air.