Capacitative Ca2+ entry in enteric glia induced by thapsigargin and extracellular ATP.
Mobilization of intracellular Ca2+ stores is coupled to Ca2+ influx across the plasma membrane, a process termed capacitative Ca2+ entry. Capacitative Ca2+ entry was examined in cultured guinea pig enteric glia exposed to 100 microM ATP, an inositol trisphosphate-mediated Ca2+-mobilizing agonist, and to 1 microM thapsigargin, an inhibitor of microsomal Ca2+ ATPase. Both agents caused mobilization of intracellular Ca2+ stores followed by influx of extracellular Ca2+. This capacitative Ca2+ influx was inhibited by Ni2+ (88 +/- 1%) and by La3+ (87 +/- 1%) but was not affected by L- or N-type Ca2+ channel blockers. Pretreatment of glia with 100 nM phorbol 12-myristate 13-acetate for 24 h decreased capacitative Ca2+ entry by 48 +/- 2%. Chelerythrine (0.1-10 microM), a specific antagonist of protein kinase C (PKC), dose dependently inhibited capacitative Ca2+ entry. The nitric oxide synthase inhibitor NG-nitro-L-arginine (1 mM) decreased Ca2+ influx by 42 +/- 1%. Capacitative Ca2+ entry was inhibited to a similar degree by the guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Capacitative Ca2+ entry occurs in enteric glial cells via lanthanum-inhibitable channels through a process regulated by PKC and nitric oxide.
Sarosi
G A
GA
Department of Surgery, University of Michigan, Ann Arbor, Michigan 48109-0331, USA.
Barnhart
D C
DC
Turner
D J
DJ
Mulholland
M W
MW
D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000470:Alkaloids; D000818:Animals; D001464:Barium / Q000494:pharmacology; D053119:Benzophenanthridines; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D009197:Myenteric Plexus / Q000502:physiology*; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology*; D010617:Phenanthridines / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology*
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D010617:Phenanthridines; D001464:Barium; D019284:Thapsigargin; D007811:Lanthanum; D000255:Adenosine Triphosphate; C016299:chelerythrine; D000252:Calcium-Transporting ATPases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium