Ultrasonic effects on alveolar macrophages in suspension

Rabbit alveolar macrophages in suspension were exposed to 5 or 10 min of continuous 2-MHz ultrasound with 5, 10, and 15 W/cm2 spatial average intensities. Viability as determined by dye exclusion decreased with increasing intensity. Pressure experiments indicated that this was a result of acoustic cavitation. Ultrasound induced clumping of cells and often reduced membrane ruffling. Some cells were disintegrated. Cells that appeared to be otherwise intact had swollen mitochondria with ruptured cristae.