The H2O2-generating enzyme, xanthine oxidase, decreases luminal Ca2+ content of the IP3-sensitive Ca2+ store in vascular endothelial cells

Microcirculation. 1995 Aug;2(2):195-203. doi: 10.3109/10739689509146767.


Objective: Xanthine oxidase inhibits agonist-stimulated Ca2+ signaling in calf pulmonary artery endothelial cells by an H2O2-dependent mechanism. We investigated the effect of xanthine oxidase on luminal Ca2+ content of the inositol-1,4,5-trisphosphate (IP3)-sensitive Ca2+ store.

Methods: Luminal Ca2+ content was estimated from the net release of Ca2+ activated by 2,5-di-t-butylhydroquinone (BHQ), an inhibitor of microsomal Ca2+ pumps.

Results: Initially, xanthine oxidase depleted the IP3-sensitive Ca2+ store of releasable Ca2+, but with more prolonged incubation, the enzyme also depleted non-IP3-sensitive stores. In addition, xanthine oxidase inhibited capacitative Ca2+ influx. Similar results were observed when thapsigargin was substituted for BHQ.

Conclusions: Depletion of luminal Ca2+ content within the IP3-sensitive Ca2+ store contributes to xanthine oxidase inhibition of Ca2+ signaling in vascular endothelial cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cattle
  • Cells, Cultured
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Hydrogen Peroxide / metabolism*
  • Hydroquinones / pharmacology
  • Inositol 1,4,5-Trisphosphate / physiology*
  • Reactive Oxygen Species
  • Terpenes / pharmacology
  • Thapsigargin
  • Xanthine Oxidase / antagonists & inhibitors
  • Xanthine Oxidase / metabolism*


  • Enzyme Inhibitors
  • Hydroquinones
  • Reactive Oxygen Species
  • Terpenes
  • 2,5-di-tert-butylhydroquinone
  • Thapsigargin
  • Inositol 1,4,5-Trisphosphate
  • Hydrogen Peroxide
  • Xanthine Oxidase
  • Calcium