Objective:To investigate the effect of ultrasound on the ultrastructure and expression of P-gp of Neuroblastoma cell in order to discuss the mechanisms of ultrasound affecting the chemotherapeutic sensitivity of SK-N-SH cell. Methods:The SK-N-SH cells were divided into the experimental group and the control group. In the experimental group

the cell suspensions were exposed to ultrasound irradiation. In the control group

the cell suspensions were exposed to sham irradiation . The changes of ultrastructure of tumor cells were observed by scanning electron microscope and the expression of P-gp in two groups were detected. Results:(1) In the pictures took by scanning electron microscope

we found that: the configuration of tumor cell changed and there were some holes of different diameters on the cell membrane and the numbers of microvillus reduced or disappeared after ultrasound irradiation.(2) The result of immunocytochemisty showed the expression rate of P-gp in SK-N-SH cells in the control group was 56.23%±9.86% vs 34.86%±6.19% in the experimental group (P<0.05)

which shows the expression of P-gp in SK-N-SH cells exposed to ultrasound was lower than that of the cells exposed to sham irradiation. Conclusion:Ultrasound can damage the structure of cell membrane and reduce the expression of P-gp in SK-N-SH cells

which are the reasons for ultrasound enhancing the chemotherapeutic sensitivity of SK-N-SH cell.