Calcium entry activated by store depletion in human umbilical vein endothelial cells

M. Oike, M. Gericke, G. Droogmans, B. Nilius

Research output: Contribution to journalArticle

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Abstract

We have used the patch clamp technique combined with simultaneous measurement of intracellular Ca2+ to record ionic currents activated by depletion of intracellular Ca2+-stores in endothelial cells from human umbilical veins. Two protocols were used to release Ca2+ from intracellular stores, i.e. loading of the cells via the patch pipette with Ins(1,4,5)P3, and extracellular application of thapsigargin. Ins(1,4,5)P3 (10 μM) evoked a transient increase in [Ca2+]i in cells exposed to Ca2+-free extracellular solutions. A subsequent reapplication of extracellular Ca2+ induced an elevation of [Ca2+]i. These changes in [Ca2+]i were very reproducible. The concomitant membrane currents were neither correlated in time nor in size with the changes in [Ca2+]i. Similar changes in [Ca2+]i and membrane currents were observed if the Ca2+-stores were depleted with thapsigargin. Activation of these currents was prevented and holding currents at -40 mV were small if store depletion was induced in the presence of 50 μM NPPB. This identifies the large currents, which are activated as a consequence of store-depletion, as mechanically activated Cl- currents, which have been described previously [1,2]. Loading the cells with Ins(1,4,5)P3 together with 10 mM BAPTA induced only a very short lasting Ca2+ transient, which was not accompanied by activation of a detectable current, even in a 10 mM Ca2+-containing extracellular solution. Also thapsigargin does not activate any membrane current if the pipette solution contains 10 mM BAPTA (ruptured patches). The contribution of Ca2+-influx to the membrane current during reapplication of 10 mM extracellular calcium to thapsigargin-pretreated cells was estimated from the first time derivative of the corresponding Ca2+ transients at different holding potentials. These current values showed strong inward rectification, with a maximal amplitude of 1.0 ± 0.3 pA at -80 mV (n = 8: membrane capacitance 59 ± 9 pF). We conclude that store depletion in endothelial cells may activate an extremely small whole-cell Ca2+ current, that is consistent with CRAC currents described in mast cells [3]. However, a non-electrogenic component and/or Ca2+-entry through a non-selective pathway cannot be ruled out.

Original languageEnglish
Pages (from-to)367-376
Number of pages10
JournalCell Calcium
Volume16
Issue number5
DOIs
Publication statusPublished - Nov 1994
Externally publishedYes

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Human Umbilical Vein Endothelial Cells
Thapsigargin
Calcium
Membranes
Patch-Clamp Techniques
Mast Cells
Endothelial Cells
1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid

All Science Journal Classification (ASJC) codes

  • Physiology
  • Molecular Biology
  • Cell Biology

Cite this

Calcium entry activated by store depletion in human umbilical vein endothelial cells. / Oike, M.; Gericke, M.; Droogmans, G.; Nilius, B.

In: Cell Calcium, Vol. 16, No. 5, 11.1994, p. 367-376.

Research output: Contribution to journalArticle

Oike, M. ; Gericke, M. ; Droogmans, G. ; Nilius, B. / Calcium entry activated by store depletion in human umbilical vein endothelial cells. In: Cell Calcium. 1994 ; Vol. 16, No. 5. pp. 367-376.
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