Sister chromatid exchanges after exposure to ultrasound and mitomycin C.

A pilot study was designed to determine whether a synergistic ability to produce sister chromatid exchanges exists between ultrasound and mitomycin C, an alkylating agent known to induce sister chromatid exchanges. Bromodeoxyuridine-containing cells from human lymphocyte cultures were randomized into one of four exposures: (1) unexposed controls, (2) 20 minutes of pulsed ultrasound (3.5 MHZ), (3) mitomycin C alone, or (4) mitomycin C and 20 minutes of pulsed ultrasound. The mean sister chromatid exchange frequencies were 6.7 control cells, 7.5 cells exposed only to ultrasound, 8.1 cells treated with both ultrasound and mitomycin C, and 10.4 cells treated with mitomycin C alone. Neither X2 tests for differences in the four distributions nor analysis of variance for interaction between ultrasound and mitomycin C was significant. Our results suggest that individuals receiving alkylating agents are not likely to be highly susceptible to any deleterious effects of ultrasound. However, these results remain tentative pending repetition of studies and development of more appropriate in vitro exposure systems.