Methods for inducing calcium mobilization in cells through the application of nanosecond pulsed electric fields ("nsPEFs") are provided. The invention also provides a method of increasing intracellular calcium in cells through the application of nsPEFs. In one embodiment of the invention, the cells are human platelets, whereby activation and aggregation of the platelets is induced. Methods for treating an injury, trauma, or loss of blood in a subject, through the application of nsPEFs are also provided.