Effect of vanadate on ATP-induced increase in intracellular calcium ion levels in human umbilical vein endothelial cells

Abstract

We investigated the effect of ammonium vanadate (vanadate) on ATP-induced increases in intracellular calcium ion level ([Ca2+]i) of human umbilical vein endothelial cells (HUVEC) by fluorescence confocal microscopic imaging using the Ca2+-sensitive probe Calcium Green 1/AM. The ATP analogue 2-methylthio-ATP (2meS-ATP), at 10μM, significantly increased the [Ca2+]i of HUVEC, and this was abolished by 1μM thapsigargin (a calcium pump inhibitor), whereas extracellular free calcium had no effect. Vanadate at 10μM also significantly increased the [Ca2+]i of HUVEC, which was abolished by 1μM thapsigargin. However, vanadate at 1μM did not exert such a significant effect. We thus examined the influence of ≤ 1μM vanadate for 24 h on 2meS-ATP-induced increase in [Ca2+]i. Vanadate significantly reduced the action of 2meS-ATP at 1μM but not at 0.1μM. Endogenously released ATP is known to induce various actions on endothelial cells. The present results suggest that vanadate exerts a regulatory influence on the function of vascular endothelial cells. © 2010 Pharmaceutical Society of Japan.