Mechanically induced calcium signal in mammary epithelial cells.

In mouse mammary epithelial cells, mechanical stimulation of a cell induced an increase of intracellular Ca2+ concentration (Ca2+i), which spread from the stimulated cell to the surrounding cells with a conduction velocity of about 10 microns/s. The Ca2+i signal was transmitted between isolated cells or separated colonies, where there was no physical contact between them. The flow of medium changed the spreading pattern of Ca2+ wave. The Ca2+ wave was induced even in Ca(2+)-free solution. These findings suggested that a certain factor was released from stimulated cell to extracellular medium and it induced the Ca2+i increase from intracellular store in the surrounding cells.