Alteration of cell membrane by stress waves in vitro

Experiments on the biological effects of laser-induced stress waves indicate that there is a transient increase in the permeability of the cell membrane. A cell viability assay (propidium iodide exclusion) shows that mouse breast sarcoma cells are viable after a stress wave. The kinetics of this transient membrane permeability are measured using time-resolved fluorescence imaging. The efflux of a membrane-impermeable fluorescent probe (calcein) following the application of a 300-bar stress wave implies that there is an increase in the membrane permeability. This efflux ceases within 80 s after a stress wave, suggesting that the membrane is no longer permeable to the fluorescent probe. Fitting the observed kinetics to a simple diffusion model yields an average initial diffusion constant of 2.2 +/- 1.3 x 10(-7) cm2/s for mouse breast sarcoma cells following the application of a laser-induced stress wave.