Dissociation between the Ca²⁺ signal and tube formation induced by vascular endothelial growth factor in bovine aortic endothelial cells

The correlation between the intracellular Ca²⁺ signal and the tube formation in collagen gels induced by vascular endothelial cell growth factor (VEGF) was investigated using cultured bovine aortic endothelial cells. The VEGF-induced sustained elevation of cytosolic Ca²⁺ concentration ([Ca²⁺](i)) was similarly inhibited by 10 μM 1-{β-[3-(4- methoxyphenyl)propyl]-4-methoxyphenethyl}-1H-imidazole hydrochloride (SKF 96365) and 10 μM troglitazone. However, 10 μM diltiazem had no effect. The basal tube formation obtained with 1% serum was augmented twofold by 100 ng/ml VEGF. SKF 96365 (0.1-10 μM) inhibited the VEGF-induced and basal tube formation, while 10 μM troglitazone or 10 μM diltiazem had no effect. The proliferation of endothelial cells was markedly inhibited by SKF 96365 but only slightly by troglitazone and diltiazem. The inhibition of tube formation by three Ca²⁺ entry blockers thus correlated with the inhibition of cell proliferation. The [Ca²⁺](i) elevation is thus not a prerequisite for VEGF to induce tube formation. (C) 2000 Elsevier Science B.V.