Porphyrin-induced enhancement of ultrasound cytotoxicity

We examined the effect of ultrasound on the murine leukaemia L1210 cell line in culture, in the presence of porphyrins varying widely in their capacity to sensitize cells to light. These porphyrins enhanced ultrasound-induced cell damage in vitro only when present in the incubation medium. When cells containing intracellular porphyrins were exposed to ultrasound, cell viability was not altered. Moreover, there was no correlation between the efficacy of a given porphyrin for light- versus ultrasound-induced cytotoxicity. Loss of viability was associated with inhibition of amino acid transport and cell fragmentation, suggesting disruption of the integrity of the cell membrane. Ultrasound-induced cell damage occurred only in the presence of cavitation nuclei.