The safety of diclofenac (DIC) use in clinical practice has been questioned because of adverse cardiovascular effects. Previous studies have indicated that DIC cause mitochondrial dysfunction and oxidative stress in heart mitochondria. The aim of this study was to investigate the protective effect of calcitriol against the mitochondrial toxicity potency of diclofenac in heart rat mitochondria. For this purpose, rat heart mitochondria were isolated with mechanical lysis and differential centrifugation. Then isolated mitochondria were pretreated with 3 different concentrations of calcitriol (2.5, 5 and 10 µM) for 5 min at 37°C, after which DIC (10 µg/ml) was added to promote deleterious effects on mitochondria. During 1 hour of incubation, using by flow cytometry and biochemical evaluations, the parameters of mitochondrial toxicity were evaluated. Our results showed that DIC (10 µg/ml) caused a significant decrease in succinate dehydrogenase (SDH) activity, mitochondrial membrane potential (MMP) collapse, and mitochondrial swelling, and a significant increase in reactive oxygen species (ROS) formation, lipid peroxidation (LP) and oxidative stress. Also, our results revealed that co-administration of calcitriol (5 and 10 µM) with diclofenac markedly ameliorates the mitochondrial toxicity effects in rat hart mitochondria. In this study, we showed that DIC impairs mitochondrial function and induces mitochondrial toxicity in rat heart isolated mitochondria, which were ameliorated by calcitriol. These findings suggest that calcitriol may be a preventive/therapeutic strategy for cardiotoxicity complications caused by DIC.
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