Heterogeneity of caffeine- and bradykinin-sensitive Ca2+ stores in vascular endothelial cells

W. F. Graier, S. Simecek, D. K. Bowles, M. Sturek

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

The filling state of Ca2+ stores in endothelial cells regulates Ca2+ entry. The functional relationship between the major Ca2+ stores [i.e. Ins(1,4,5)P3-sensitive (= bradykinin-sensitive stores, 'BsS') and caffeine-sensitive stores] is unknown. In pig right-coronary-artery endothelial cells, caffeine failed to release Ca2+ in 68% of the cells (quiet-responders), but increased bradykinin (Bk)-induced Ca2+ release 2.5-fold. In Bk-pre-stimulated cells, caffeine increased Ca2+ release upon a second stimulation with Bk 3.2-fold. In quiet-responders caffeine alone did not affect net Ca2+ storage, whereas Bk or caffeine followed by Bk decreased the intracellular Ca2+ pool to 45% and 15%, respectively. Blockade of the endoplasmic-reticulum Ca2+ pump by thapsigargin unmasked the effect of caffeine in quiet-responders, resulting in a transient increase in intracellular free Ca2+ concentration ([Ca2+](i).). In 37% of the cells caffeine alone transiently increased [Ca2+](i) and depleted BsS. This study suggests a heterogeneity in functional organization of endothelial Ca2+ stores. In quiet-responders, caffeine translocates Ca2+ towards the BsS, whereas in overt-responders caffeine empties the BsS.

Original languageEnglish (US)
Pages (from-to)637-641
Number of pages5
JournalBiochemical Journal
Volume300
Issue number3
DOIs
StatePublished - Jan 1 1994
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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