Hematoporphyrin as a Sensitizer of Cell‐damaging Effect of Ultrasound

Mouse sarcoma 180 or rat ascites hepatoma (AH) 130 cells were exposed to ultrasound (US; 1.27, 2.21 and 3.18 W/cm 2 ; 1.92 MHz) for up to 60 s in vitro in the presence or absence of hematoporphyrin (Hp; 10, 25 and 50 μg/ml). The cell‐damaging effects of treatments were determined by means of the Trypan Blue dye exclusion test. Hp alone did not show any cell‐damaging effect, whereas US alone damaged 30 and 50% of sarcoma and AH 130 cells, respectively, at the maximum intensity for 60 s. In the presence of 50 μg/ml Hp, US damaged 99 and 95% of the above tumor cells, respectively. These results show that Hp increased the sensitivity of tumor cells to US.