Ca 2+-mediated ascorbate release from coronary artery endothelial cells

Kim A. Davis, Sue E. Samson, Kelly Best, Kanwaldeep K. Mallhi, Magdalena Szewczyk, John X. Wilson, Chiu Yin Kwan, Ashok K. Grover

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

1 The addition of Ca 2+ ionophore A23187 or ATP to freshly isolated or cultured pig coronary artery endothelial cells (PCEC) potentiated the release of ascorbate (Asc). Cultured PCEC were used to characterize the Ca 2+-mediated release. An increase in Ca 2+-mediated Asc release was observed from PCEC preincubated with Asc, Asc-2-phosphate or dehydroascorbic acid (DHAA). 2 The effects of various ATP analogs and inhibition by suramin were consistent with the ATP-induced release being mediated by P2Y2-like receptors. 3 ATP-stimulated Asc release was Ca 2+-mediated because (a) ATP analogs that increased Asc release also elevated cytosolic [Ca 2+], (b) Ca 2+ ionophore A23187 and cyclopiazonic acid stimulated the Asc release, (c) removing extracellular Ca 2+ and chelating intracellular Ca 2+ inhibited the ATP-induced release, and (d) inositol-selective phospholipase C inhibitor U73122 also inhibited this release. 4 Accumulation of Asc by PCEC was examined at Asc concentrations of 10 μM (Na +-Asc symporter not saturated) and 5 mM (Na +-Asc symporter saturated). At 10 μM Asc, A23187 and ATP caused an inhibition of Asc accumulation but at 5 mM Asc, both the agents caused a stimulation. Substituting gluconate for chloride did not affect the basal Asc uptake but it abolished the effects of A23187. 5 PCEC but not pig coronary artery smooth muscle cells show a Ca 2+- mediated Asc release pathway that may be activated by agents such as ATP.

Original languageEnglish (US)
Pages (from-to)131-139
Number of pages9
JournalBritish Journal of Pharmacology
Volume147
Issue number2
DOIs
StatePublished - Jan 2006

Keywords

  • ATP
  • Dehydroascorbic acid
  • Lectin
  • Magnetic beads
  • Oxidative stress
  • P2Y2 receptors
  • Vitamin C

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