To investigate the interactions of ultrasonic waves with biological tissues, we developed and standardized several in vitro models. Using these systems - artificial stones, human erythrocytes, L1210 mouse leukemia cells, multicellular spheroids, cavitation assay - we are able to elucidate the mechanisms of interaction as well as the cause of clinically observed side effects.
The application of extracorporeal generated shock waves in medicine for the fragmentation of human kidney and gall stones proved to be a very successful technique. Shock wave lithotripsy, however, is not free of tissue damaging side effects. One major mechanism for the fragmentation of stones as well as for the side effects is cavitation, ie. the formation and movement of bubbles in liquids exposed to tensile forces. Collapse of cavitation bubbIes is accompanied by local "hot spots" of several 1,000 K, thus generating free radicals. We investigated the contribution of these free radicals to cellular injury by varying the cellular amount of a well known scavenger of free radicals, α-tocopherol.
