Lysine and polylysine: correlation of their effects on polyphosphoinositides in vitro with ototoxic action in vivo.

Low concentrations of poly-L-lysine, a polycationic hydrophilic molecule, caused a large expansion of polyphosphoinositide monolayers and produced a significant loss of cochlear microphonic potentials in perilymphatic perfusions in the guinea pig. In contrast, the monomeric L-lysine had only slight effects on polyphosphoinositide monolayers and did not affect cochlear microphonic potentials even at concentrations as high as 10 mM. These data substantiate the hypothesis that the expansion of polyphosphoinositide monolayers by a drug is an indicator of its ototoxicity.