Effects of sonodynamic and photodynamic treatment on cellular thiol levels

Exposure of murine leukemia L1210 cells to ultrasound in vitro resulted in cell fragmentation; cells which survived this treatment were 100% viable and showed a transient decrease in intracellular thiol pools (expressed as glutathione equivalents). Depletion of thiol pools became progressively greater with increasing exposure of cells to ultrasound; this was not associated with leakage of thiols into the medium. Biochemically elevating glutathione levels or sonication in the presence of the anti-oxidant trolox offered only a minor degree of protection against sonotoxicity. Photodynamic therapy also resulted in depletion of intracellular thiol levels, and loss of cell viability. In the presence of trolox, both effects were reversed, although elevation of intracellular thiol levels did not protect cells from phototoxicity.