Covalent binding of cisplatin impairs the function of Na(+)/K(+)-ATPase by binding to its cytoplasmic part.

This study was aimed at verifying the hypothesis that acute kidney failure accompanying cisplatin administration in the cancer therapy could be due to cisplatin interaction with the cytoplasmic part of Na(+)/K(+)-ATPase. Our results demonstrated that cisplatin-binding caused inhibition of Na(+)/K(+)-ATPase, in contrast to other platinated chemotherapeutics such as carboplatin and oxaliplatin, which are known to be much less nephrotoxic. To acquire more detailed structural information, we performed a series of experiments with the isolated large cytoplasmic segment connecting transmembrane helices 4 and 5 (C45 loop) of Na(+)/K(+)-ATPase. Electrochemistry showed that cisplatin is bound to the cysteine residues of the C45 loop, mass spectrometry revealed a modification of the C45 peptide fragment GSHMASLEAVETLGSTSTICSDK, which contains the conserved phosphorylated residue Asp369. Hence, we hypothesize that binding of cisplatin to Cys367 can cause sterical obstruction during the phosphorylation or dephosphorylation step of the Na(+)/K(+)-ATPase catalytic cycle.

Time-course evaluation of oxidative stress-related biomarkers after renal transplantation.

Patients with chronic renal disease have a high prevalence of oxidative stress (OS), which is associated with the cardiovascular complications occurring in this population. The restoration of kidney function after kidney transplantation (KT) can lead to reduction in the metabolic abnormalities and elimination of the OS. Time-dependent changes in OS-related markers and specific kidney function and metabolic parameters were evaluated in patients (N = 39; 23 males; 16 females; mean age = 57 ± 10 years) before (day 0) and after KT (day 1, 7, 30, 90, and 180) to monitor the graft. In particular, total antioxidant capacity (TAC), levels of advanced oxidation protein products (AOPP), lipid peroxidation as thiobarbituric acid-reactive substances (TBARS) and reduced glutathione (GSH); activities of glutathione peroxidase, catalase, and superoxide dismutase; and kidney function markers were measured. AOPP, TAC, and TBARS were significantly decreased, whereas GSH was significantly increased after KT. Antioxidant enzyme activities were not significantly changed during the monitored period after KT. Apropos specific kidney function markers and glomerular filtration significantly increased and creatinine level significantly decreased after transplantation. Changes in high-density lipoprotein cholesterol were also found. Our results show that successful KT results in normalization of the antioxidant status and lipid metabolism that is connected with both improved renal function and reduced cardiovascular complications.