Gentamicin-induced mitochondrial damage in inner ear sensory cells of the lizard Calotes versicolor.

Earlier morphological and histochemical studies on the effects on inner ear sensory cells caused by aminoglycoside antibiotics have failed to give sufficient information of the genesis of these effects. The present study was focused on the phases of progessive mitochondrial changes in sensory cells of the the lizard basilar papilla induced by consecutive large doses of gentamicin. The mitochondria react by swelling, changes in the configuration and number of the cristae and formation of matrical inclusions. Myelin figures are a consistent finding in degenerating cells after gentamicin exposure. These are shown to be derived from changed mitochondria. The final product is an "onion-like" structure which is built of primitive membranes. There is a marked difference in reaction to the damage between individual mitochondria in the same cell. This difference is also evident between individual sensory cells in the same specimen. By studying the phases of the mitochondrial breakdown process in the sensory cell, some additional information on the changes in cell metabolism caused by ototoxic drugs, may be extracted.