HMOX1 and acute kidney injury: Taking all these mentioned things together, the aim of this study was to perform the immunohistochemical analysis of 4-HNE, NGAL, and HO-1 tissue expression after apocynin treatment and hyperbaric oxygenation preconditioning, applied as single or combined protocol, in postischemic acute kidney injury, induced in spontaneously hypertensive rats (SHR).