NAADP mediates ATP-induced Ca2+ signals in astrocytes

► NAADP as a new intracellular second messenger in astrocytes. ► NAADP receptors are present in lysosome-related vesicles. ► NAADP-AM increases intracellular calcium concentration. ► The lysosomal disruptor compound glycyl-l-phenylalanine 2-naphthylamide inhibits NAADP-AM responses. ► NAADP mediates ATP and ET-1 but not bradykinin-induced calcium mobilization from lysosome-related stores.