title: Exogenous ATP raises cytoplasmic free calcium in fura-2 loaded piglet aortic endothelial cells.
abstract: Cultured piglet endothelial cells were grown to confluence on glass coverslips and loaded with the fluorescent Ca2+ indicator, fura-2. Using a dual-wavelength excitation fluorescence spectrophotometer it was found that ATP caused a rapid transient elevation in [Ca2+]i in the presence of extracellular calcium which decreased to a maintained elevated level. With no extracellular calcium ATP evoked a similar transient increase which returned to the basal level. Addition of 50 mM K+ had no effect on [Ca2+]i or on the effect of ATP on [Ca2+]i in the presence of extracellular Ca2+. The data suggest that ATP causes both discharge of calcium from an intracellular pool and influx across the plasma membrane although this is unlikely to be via a voltage-operated channel. ATP stimulated simultaneously the production of PGI2 to a similar extent in the presence or absence of extracellular calcium. Elevated [Ca2+]i may be an important activation pathway in the endothelial cell.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001572:Benzofurans; D002118:Calcium / Q000032:analysis*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000032:analysis*; D004727:Endothelium / Q000378:metabolism*; D011464:Epoprostenol / Q000096:biosynthesis; D004987:Ethers / Q000494:pharmacology; D005453:Fluorescence; D016257:Fura-2; D015759:Ionomycin; D008345:Manganese / Q000378:metabolism; D013552:Swine
chemical_list: D001572:Benzofurans; D004987:Ethers; D008345:Manganese; D015759:Ionomycin; D000255:Adenosine Triphosphate; D011464:Epoprostenol; D002118:Calcium; D016257:Fura-2