Melatonin elevates intracellular free calcium in human platelets by inositol 1,4,5-trisphosphate independent mechanism

► Melatonin at higher concentration elevates intracellular Ca2+ in human platelets. ► Melatonin action is independent of PLC-IP3 axis, as well as acidic calcium stores. ► Melatonin evokes release of Ca2+ from platelet mitochondrial stores. ► Store-operated calcium entry is stimulated in presence of melatonin. ► Melatonin action in platelets is not associated with inhibition of SERCA.