Cytogenetic effects of continuous therapeutic ultrasound waves on human lymphocytes in G0 phase of cell cycle

In spite of wide spread investigations performed, the biological effects of ultrasound waves, specially on DNA molecule has not been fully understood. Since any alteration in DNA molecule can lead to chromosome abnormality, the study of clastogoenic effects of ultrasound is important. In this study, the effect of 1MHz frequency continuous waves with the power of 0.5, 1 and 1.5 Watts on G0- human lymphocytes was investigated. Lymphocytes were separated from heparinized peripheral blood by using lymphocyte separation medium and then were exposed to ultrasound waves. Exposed samples were cultured in RPMI-1640 treated with phytohaemaglutinin. (PHA) and then binuclei cells were harvested using cytochalasin B. For each sample 1000 binuclei were examined for the presence of micronuclei. Results obtained from control, sham control and samples exposed to various ultrasound waves with different powers from 0.5 to 1.5 W showed that there is no statistical difference between the frequency of micronuclei observed for sham, control and samples to 0.5 W. However cells exposed to 1 and 1.5 W ultrasound waves showed significantly higher micronuclei frequency compared to control and sham groups (P<0.05). In the present study, because of short exposure duration, temperature rise and hence thermal effect on cells was negligible. Therefore, mechanical process of ultrasound waves including chemical effects which lead to free radical formation (Probably due to cavitation in exposure field) and mechanical vibration of large molecules which are fragile structures may play a role in chromosomal aberration and micronuclei formation.