[Effect of ATP on cytosolic free calcium in single porcine pulmonary artery endothelial cell in primary culture].

Effect of ATP on cytosolic free calcium ([Ca2+]i) in single porcine pulmonary artery endothelial cell was studied. Using a dual-wavelength excitation fluorescence spectrophotometer, it was found that ATP evoked a rapid rise in [Ca2+]i followed by a slightly maintained increase. Removal of extracellular Ca2+ abolished the maintained increase without obvious effect on the initial transient. These results suggest that ATP stimulates both calcium release from intracellular calcium pool (s) and calcium influx across the plasma membrane.