Requirement of calcium ions for cell degeneration with a toxin (vibriolysin) from Vibrio parahaemolyticus.

A highly purified toxin (vibriolysin) from Vibrio parahaemolyticus caused degeneration of cell shape, such as bleb and balloon formation, of mouse myocardial cells and mouse melanoma cells in culture. An extracellular Ca2+ concentration of more than 10(-6) M was necessary for the degeneration of cell shape, but extracellular Mg2+, Na+, and K+ were not necessary. In the presence of extracellular Ca2+, vibriolysin also caused full contraction of myofibrils of mouse myocardial cells and reduction of both actin cables and tubulin networks of mouse melanoma cells. Vibriolysin also caused excess uptake of Ca2+ from the incubation medium by mouse myocardial cells and mouse melanoma cells. Chick myocardial cells, which show neither degeneration of cell shape nor full contraction of myofibrils, did not take up excess 45Ca2+ in the presence of vibriolysin. These findings suggest that the vibriolysin-induced degeneration of cell shape of mouse myocardial cells and mouse melanoma cells is due to excess uptake of Ca2+ from the incubation medium by the cells.