Ultrasonically induced cell damage enhanced by photofrin II: mechanism of sonodynamic activation.

UNLABELLED: Ultrasonically induced cell damage and active oxygen generation with photofrin II (PF) were compared in the same in vitro insonation setup.

MATERIALS AND

METHODS

Sarcoma 180 cells suspended in air-saturated PBS were exposed to ultrasound for up to 60 seconds in the presence and absence of PF. The viability was determined by the Trypan Blue exclusion test. Ultrasonically induced active oxygen generation in the presence and absence of PF in air-saturated aqueous solutions of 50 mM 2,2,6,6-tetramethyl-4-piperidone was detected by electron spin resonance (ESR) spectrum.

RESULTS

Significant enhancement of the rates of both ultrasonically induced cell damage and nitroxide generation was demonstrated with 20-80 micrograms/ml PF. Both rates correlated very well. The enhancement of both rates with PF was suppressed by 10 mM histidine.

CONCLUSION

These results may suggest that ultrasonically generated active oxygen plays a primary role in ultrasonically induced cell damage in the presence of PF.