Gentamicin-induced cytotoxicity involves protein kinase C activation, glutathione extrusion and malondialdehyde production in an immortalized cell line from the organ of corti.

The objective of the present study was to investigate the biochemical mechanisms underlying gentamicin cytotoxicity in OC-k3 cells derived from an immortalized cell line developed from the organ of Corti of transgenic mice. Administration of 50 microM gentamicin significantly reduced cell proliferation and viability, as well as initiating morphological changes associated with apoptosis. Protein kinase C (PKC) alpha activity was increased in gentamicin-treated cells, peaking 15 min after dosing (+138.2%). This PKCalpha increase was followed by a rise of glutathione (GSH) efflux and a concomitant 29% decrease in intracellular GSH levels at 30 min. PKCalpha-specific inhibitors blocked these cytotoxic effects. Gentamicin also increased malondialdehyde levels, while N-acetylcysteine, GSH and ascorbic acid prevented gentamicin-induced cell death. These findings suggest that gentamicin cytotoxicity involves a production of intracellular reactive oxygen species and a concomitant PKC-dependent fall of intracellular scavenging abilities (GSH), events that together drive cells to undergo apoptosis.