Exposure of endothelial cells to cyclic strain induces elevations of cytosolic Ca2+ concentration through mobilization of intracellular and extracellular pools

Oscar R. Rosales, Carlos M. Isales, Paula Q. Barrett, Colleen Brophy, Bauer E. Sumpio

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

We have previously reported that exposure of endothelial cells to cyclic strain elicited a rapid but transient generation of inositol 1,4,5-trisphosphate (IP3), which reached a peak 10 s after the initiation of cyclic deformation. To address the effect of cyclic strain on intracellular Ca2+ concentration ([Ca2+]i) and its temporal relationship to IP3 generation, confluent bovine aortic endothelial cells were grown on flexible membranes, loaded with aequorin and the membranes placed in a custom-designed flow-through chamber. The chamber was housed inside a photomultiplier tube, and vacuum was utilized to deform the membranes. Our results indicate that the initiation of 10% average strain induced a rapid increase in [Ca2+]i which contained two distinct components: a large initial peak 12 s after the initiation of stretch which closely followed the IP3 peak, and a subsequent lower but sustained phase. Pretreatment with 5 μM GdCl3 for 10 min or nominally Ca2+-free medium (CFM) for 3 min reduced the magnitude of the initial rise and abolished the sustained phase. Repetitive 10 % average strain at a frequency of 60 cycles/min also elicited a single IP3 peak at 10 s. However, there was also a large initial [Ca2+Ji peak followed by multiple smaller transient [Ca2+]i elevations. Preincubation with 5μM GdCl3 or CFM diminished the initial [Ca2+]i transient and markedly inhibited the late-phase component. Preincubation with 25 μM 2,5-di-(t-butyl)-1,4-benzohydroquinone (BHQ) attenuated the initial [Ca2+]i transient. Cyclic-strain-mediated IP3 formation in confluent endothelial cells at 10 s, however, was not modified by pretreatment with 25 μM BHQ, 500 μM NiCl2, 10 nM charybdotoxin, 5 μM GdCl3 or CFM. We conclude that in endothelial cells exposed to cyclic strain, Ca2+ enters the cytosol from intracellular and extracellular pools but IP3 formation is not dependent on Ca2+ entry via the plasma membrane.

Original languageEnglish (US)
Pages (from-to)385-392
Number of pages8
JournalBiochemical Journal
Volume326
Issue number2
DOIs
StatePublished - Sep 1 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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