Calcium mobilization by nicotinic acid adenine dinucleotide phosphate (NAADP) in rat astrocytes

• Published in: Cell calcium (Edinburgh) 2006-02, Vol.39 (2), p.143-153
• Main Authors: Singaravelu, Karthika, Deitmer, Joachim W.
• Format: Article
• Language: English
• Subjects: Animals; Astrocytes - drug effects; Astrocytes - metabolism; Calcium Signaling - drug effects; Calcium Signaling - physiology; Calcium stores; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone - pharmacology; Cells, Cultured; Cyclopiazonic acid; Dipeptides - pharmacology; Endoplasmic reticulum; Fluorescent Dyes; Fura-2; In Vitro Techniques; Indoles - pharmacology; Inositol Phosphates - metabolism; Ionomycin; Ionomycin - pharmacology; Macrolides - pharmacology; NADP - analogs & derivatives; NADP - pharmacology; Purinergic P2 Receptor Antagonists; Rats; Receptors, Purinergic P2 - metabolism; Type C Phospholipases - metabolism
• ISSN: 0143-4160; 1532-1991
• DOI: 10.1016/j.ceca.2005.10.001

Nicotinic acid adenine dinucleotide phosphate (NAADP) has been shown to release intracellular Ca 2+ in several types of cells. We have used Ca 2+-sensitive fluorescent dyes (Fura-2, Fluo-4) to measure intracellular Ca 2+ in astrocytes in culture and in situ. Bath-applied NAADP elicited a reversible and concentration-dependent Ca 2+ rise in up to 90% of astrocytes in culture (EC 50 = 7 μM). The NAADP-evoked Ca 2+ rise was maintained in the absence of extracellular Ca 2+, but was suppressed after depleting the Ca 2+ stores of the ER with ATP (20 μM), with cyclopiazonic acid (10 μM) or with ionomycin (5 μM). P 2 receptor antagonist pyridoxalphosphate-6-azophenyl-2′4′-disulfonic acid (PPADS, 100 μM), IP 3 receptor blocker 2-aminoethoxydiphenyl borate (2-APB, 100 μM) and PLC inhibitor U73122 (10 μM) also reduced or suppressed the NAADP-evoked Ca 2+ rise. NAADP still evoked a Ca 2+ response after application of glycyl- l-phenylalanine-β-naphthylamide (GPN, 200 μM), which permeabilizes lysosomes, or preincubation with H +-ATPase inhibitor bafilomycin A1 (4 μM) and of p-trifluoromethoxy carbonyl cyanide phenylhydrazone (FCCP, 2 μM), that impairs mitochondrial Ca 2+ handling. In acute brain slices, NAADP (10 μM) evoked Ca 2+ transients in cerebellar Bergmann glial cells and in hippocampal astrocytes. Our results suggest that NAADP recruits Ca 2+ from inositol 1,4,5-trisphosphate-sensitive Ca 2+ stores in mammalian astrocytes, at least partly by activating metabotropic P 2Y receptors.