Figure 1: Time course of ATP release (a) and intracellular Ca2+ responses (b) induced by 50% hypotonic shock of HMC-1 cells in Ca2+-containing (filled squares ( ) or solid line ( ), resp.) and in Ca2+-free solutions (open circles ( ) of broken line ( ), resp.). Data represent averages of measurements ± SEM. The respective curves in (a) and (b) are not significantly different on the basis of .