Comparison of iohexol and iodixanol induced nephrotoxicity, mitochondrial damage and mitophagy in a new contrast-induced acute kidney injury rat model

Recent progress in angiography and interventional therapy has revived interest in comparison of nephrotoxicity of low-or iso-osmolar contrast media, but detailed mechanisms and effective treatments of contrast-induced acute kidney injury (CI-AKI) remain elusive. We established a new model of CI-AKI and compared the nephrotoxicity of iohexol and iodixanol with a focus on renal oxidative stress, mitochondrial damage and mitophagy. Our results showed that 48-h dehydration plus furosemide injection before iohexol administration successfully induced CI-AKI in rats. Compared with iodixanol, iohexol induced a greater decrease in renal function, more severe morphological damage and mitochondrial ultrastructural changes, an increased number of apoptotic cells, decreased antioxidative enzymes with activation of NLRP3 inflammasome in renal tissue. Renal contrast media kinetics showed the immediate excretion of iohexol and the transient renal accumulation of iodixanol. Plasma mtDNA Tc numbers were positively correlated with markers of renal mitochondrial disruption but negatively correlated with the level of serum creatinine and the score of tubular injury. Of note, iodixanol appeared to induce a stronger activation of mitophagy than iohexol, evidenced by greater protein levels of LC3II and PINK1/Parkin in the renal tissue of iodixanol-treated rats. Taken together, our results indicate that iohexol induced more severe nephrotoxicity than iodixanol in vivo due to apoptosis, destruction of antioxidative defense machinery, activation of NLRP3 inflammasome, mitochondrial damage and mitophagy. Plasma mtDNA may serve as a biological marker for renal mitochondrial disruption and damage in CI-AKI. Antioxidative defense and mitophagy are involved in the process of CI-AKI and may be promising targets of therapies.