Reactive oxygen species (ROS) have been implicated in cyclosporin A (CsA) nephrotoxicity. As mitochondria are one of the main sources of ROS in cells, we evaluated the role of CsA in mitochondrial structure and function in LLC-PK1 cells. We incubated cells with CsA 1 µM for 24 hours and studies were performed with flow citometry and confocal microscopy. We studied mitochondrial NAD(P)H content, superoxide anion (O2.-) production (MitoSOX Red), oxidation of cardiolipin of inner mitochondrial membrane (NAO) and mitochondrial membrane potential (DIOC2(3)). Also we analyzed the intracellular ROS synthesis (H2DCF-DA) and reduced glutation (GSH) of cells. Our results showed that CsA decreased NAD(P)H and membrane potential, and increased O2.- in mitochondria. CsA also provoked oxidation of cardiolipin. Furthermore, CsA increased intracellular ROS production and decreased GSH content. These results suggest that CsA has crucial effects in mitochondria. CsA modified mitochondrial physiology through the decrease of antioxidant mitochondrial compounds as NAD(P)H and the dissipation of mitochondrial membrane potential and increase of oxidants as O2.-. Also, CsA alters lipidic structure of inner mitochondrial membrane through the oxidation of cardiolipin. These effects trigger a chain of events that favour intracellular synthesis of ROS and depletion of GSH that can compromise cellular viability. Nephrotoxic cellular effects of CsA can be explained, at least in part, through its influence on mitochondrial functionalism.

Estudiamos el efecto de la ciclosporina A (CsA) sobre la estructura y función mitocondrial en células LLC-PK1. Las células se incubaron durante 24 horas con CsA 1 ìM y se analizó la producción de anión superóxido, contenido de NAD(P)H, oxidación de cardiolipina y potencial de membrana mitocondrial; además se estudió la formación de radicales libres y el contenido de glutatión reducido intracelular. Nuestros resultados demuestran que la CsA provocó un aumento del anión superóxido mitocondrial de modo paralelo al descenso de NAD(P)H; además, se produjo oxidación de la cardiolipina de la membrana interna y un descenso del potencial de membrana mitocondrial. Finalmente, observamos un aumento de la producción de radicales libres intracelulares y un descenso del glutatión reducido. En conclusión, la CsA produce modificaciones importantes en la fisiología y estructura mitocondrial con aumento de la síntesis de especies reactivas de oxígeno y descenso de la capacidad antioxidante, hechos que podrían justificar la toxicidad celular de la droga.