Prophylactic effect of ethyl pyruvate on renal ischemia/reperfusion injury mediated through oxidative stress

As oxidative stress (OXS) has been shown to play a primary role in renal ischemia/reperfusion injury (RIRI), we investigated whether antioxidant such as ethyl pyruvate (EPy) might effectively prevent RIRI. Possible prophylactic effects of EPy and mannitol (Mann), one of perioperative agents often used, were tested against harmful OXS in vitro.

Hydrogen peroxide (H₂O₂) was used to exert OXS on the renal proximal tubular MDCK cells. Severity of OXS and protective effects of EPy and Mann were assessed by lipid peroxidation assay and cell viability test, respectively. The cytotoxic mechanism of H₂O₂ was explored by examining the status of glycolysis, metabolic signaling pathways, cell cycle, and induction of apoptosis.

Although H₂O₂ (500 µM) increased OXS by ~ 3.5 times of controls, EPy (1 mM) fully reduced it to the basal level. Cell viability declined to merely 10% by H₂O₂ was regained to > 90% with EPy. Hexokinase activity and ATP level also declined significantly by H₂O₂, but they sustained 80-90% with EPy. Additionally, H₂O₂ led to the modulations of metabolic signaling regulators, a G₁ cell cycle arrest, and induction of apoptosis, which were yet prevented with EPy. Unlike EPy, Mann had virtually little effects.

OXS can indeed lead to the significant cell viability reduction through its adverse cellular effects, ultimately resulting in RIRI. However, EPy appears to prevent these effects and protect MDCK cells, while Mann does not. Thus, EPy could be a more effective prophylactic renoprotective agent (than Mann) against oxidative renal cell injury including RIRI.