Hypoxia increases cytosolic free calcium in porcine pulmonary arterial endothelial cells.

Alteration of cytosolic free calcium ([Ca2+]i) in hypoxia was studied with fluorescent probe, Fura-2 in cultured porcine pulmonary arterial endothelial cells. It was found that hypoxia caused by bubbling the cell suspension with 100% N2 increased [Ca2+]i in endothelial cells by 90 +/- 20% (n = 8, P < 0.05), but didn't affect that in a Ca(2+)-free buffer, La3+ (2 x 10(-5) mol/L) inhibited the hypoxia-induced increment in [Ca2+]i, whereas verapamil (10(-8) mol/L) didn't. These findings suggest that hypoxia could induce Ca2+ influx in pulmonary arterial endothelial cells, which might play an important role in vascular response to hypoxia.