Calcium mobilization by nicotinic acid adenine dinucleotide phosphate (NAADP) in rat astrocytes.
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 microM). 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 microM), with cyclopiazonic acid (10 microM) or with ionomycin (5 microM). P(2) receptor antagonist pyridoxalphosphate-6-azophenyl-2'4'-disulfonic acid (PPADS, 100 microM), IP(3) receptor blocker 2-aminoethoxydiphenyl borate (2-APB, 100 microM) and PLC inhibitor U73122 (10 microM) also reduced or suppressed the NAADP-evoked Ca(2+) rise. NAADP still evoked a Ca(2+) response after application of glycyl-l-phenylalanine-beta-naphthylamide (GPN, 200 microM), which permeabilizes lysosomes, or preincubation with H(+)-ATPase inhibitor bafilomycin A1 (4 microM) and of p-trifluoromethoxy carbonyl cyanide phenylhydrazone (FCCP, 2 microM), that impairs mitochondrial Ca(2+) handling. In acute brain slices, NAADP (10 microM) 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(2)Y receptors.
Singaravelu
Karthika
K
Abteilung für Allgemeine Zoologie, FB Biologie, TU Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern, Germany. karthika@rhrk.uni-kl.de
Deitmer
Joachim W
JW
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D004151:Dipeptides / Q000494:pharmacology; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology; D009249:NADP / Q000031:analogs & derivatives* / Q000494:pharmacology; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D004151:Dipeptides; D005456:Fluorescent Dyes; D007211:Indoles; D007295:Inositol Phosphates; D018942:Macrolides; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; C041865:glycylphenylalanine 2-naphthylamide; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D009249:NADP; C024376:NAADP; D015759:Ionomycin; C040929:bafilomycin A1; D010738:Type C Phospholipases; C000543:cyclopiazonic acid