Cephaloridine Induces Translocation of Protein Kinase C δ Into Mitochondria and Enhances Mitochondrial Generation of Free Radicals in the Kidney Cortex of Rats Causing Renal Dysfunction

Abstract

We have previously reported that the enhancement of free radical generation in mitochondria isolated from the kidney cortex of rats exposed to cephaloridine (CER) is probably mediated by the activation of protein kinase C (PKC). We examined which isoenzymes of PKC might be involved in the development of nephrotoxicity induced by CER in rats. The CER-induced renal dysfunction observed 24 h after its injection was prevented by a potent antioxidant DPPD and well-known PKC inhibitors like H-7 and rottlerin. At 1.5 and 3.5 h after the CER injection, the free radical generation was increased markedly and this was associated with translocation of PKCδ into the mitochondria of renal cortex tissue. Pretreatment of rats with H-7, a PKC inhibitor, significantly inhibited the CER-derived increase in mitochondrial generation of free radicals, suggesting that H-7 probably gets into the mitochondria and inhibits the activity of translocated PKC within the mitochondria. It was also shown that pretreatment of rats with rottlerin, a specific inhibitor of PKCδ, suppressed the early translocation of PKCδ into mitochondria and inhibited the CER-derived development of renal dysfunction. These results suggest that the CER-derived early translocation of PKCδ into mitochondria probably leads to the enhanced production of free radicals through the mitochondrial respiratory chain during the development of the nephrotoxicity caused by CER. Understanding the role of PKCδ in mitochondria may provide an important clue to the molecular mechanisms of mitochondrial production of reactive oxygen species and the free radical-induced renal failure in rats treated with CER. Keywords:: cephaloridine, nephrotoxicity, translocation of protein kinase C δ, mitochondria, free radical