Involvement of ultrasonically induced cavitation in the production of hind limb paralysis of the mouse neonate.

The exposure conditions which produce hind limb paralysis in 10%, 50%, and 90% of mouse neonate specimens exposed to 1-MHz ultrasound at 10 ø C and at 1and 16-atm hydrostatic pressure were determined for the intensity range 86-289 W/cm 2. The change in the exposure duration for 50% of the specimens paralyzed resulting from pressurization to 16 atm was negligible at 86 and 144 W/em 2 but was almost a factor of 2 increase at 289 W/era 2. Pressurization suppressed the observed half-harmonic received signal at all intensities. These results uggest that eavitation may influence the production ofthe hind limb paralysis produced in the neonate at 1 atm and at 289 W/em 2.