evidence: Data are presented as mean ± SD; no significant differences were observed between groups
intervention: Helium preconditioning (3 × 5 min of 70 % helium and 30 % oxygen) was applied before aortic cross clamping; postconditioning (15 min of helium) was applied before release of the aortic cross clamp.
comparator: no helium
outcome: activation of p38 MAPK, ERK 1/2 or levels of HSP27 and PKC-? in the human heart