Metabolomic Investigations And Effect Of Saturated Hydrogen Saline On Ischemia/Reperfusion Kidney Injury

Objective: In order to further understand the metabolomic changes ofischemia/reperfusion (I/R) induced acute kidney injury (AKI) and the protective effect ofsaturated hydrogen saline on AKI, our study was performed.Methods: Kidney tissues and serum samples were collected at different timepointsfrom three groups of rats, including control group, I/R group and L-carnitine pretreatedgroup. High performance liquid chromatography coupled with mass spectrometry(HPLC/MS) based metabolomics approach was applied to investigate the characteristic ofI/R induced AKI and the protective effects of L-carnitine in rat kidney I/R model.Antioxidant enzymatic activity and Phospholipase A₂ (PLA₂) activity were determined tovalidate the metabolic outcomes. In part two, rats with 45 min occlusion and 24 hreperfusion of the bilateral renal arteries were treated with saturated hydrogen saline (SHS)intravenously with different dosages at different timepoints. Renal functions, necrosisindex of tubular epithelial cells, levels of oxidative stress as well as endoplasmic reticulumstress were measured at different groups of rats.Results: Changes in the pattern of endogenous metabolites as a result of kidney I/Rinjury were readily detected as early as 2 h after reperfusion, when was earlier than theincrease of BUN and Scr. Twenty-eight differential endogenous metabolites werediscovered and structurally identified by MSn analysis. After I/R injury, lysophospholipids,FFAs and nitrotyrosine significantly increased while carnitine and acetyl-carnitine greatlydecreased compared to the control group. PLA₂ activity and MDA level also increasedwhile SOD activity decreased in kidney I/R injury rats. SHS administered at 30 min priorto reperfusion intravenously significantly relieved IR induced kidney injury. When ratswere given SHS at 30 min after reperfusion, their renal function made no significantdifference from those untreated IR rats. SHS significantly attenuated oxidation of lipid,protein and DNA, as well as expression of GRP78, CHOP, phosphorylation of eIF2|áandPERK and activation of caspase 12.Conclusion: I/R induced AKI could be characterized by oxidative stress and changesin lipid metabolism through metabolomic investigation. SHS treated at 30 min beforereperfusion was able to alleviate oxidative stress and ERS in rat kidney IR injury model.