Nitric oxide induces transient Ca2+ changes in endothelial cells independent of cGMP

J Cell Physiol. 1997 Sep;172(3):296-305. doi: 10.1002/(SICI)1097-4652(199709)172:3<296::AID-JCP3>3.0.CO;2-J.

Abstract

Ca2+ changes induced by nitric oxide (NO.) were investigated in cultured human endothelial cells. Sodium nitroprusside (SNP) (1-100 mumol/L) and S-Nitroso-N-acetylpenicillamine (SNAP) (100 mumol/L) were used as NO. donors. The cytoplasmatic Ca2+ concentration was calculated using ratiometric FURA2 fluorescence measurements. Both NO. donors caused transient oscillatory Ca2+ changes, which were not detectable in the presence of oxyhemoglobin (50 mumol/L). Digital ratio imaging revealed initiation sites within cells where Ca2+ increases started spreading, which indicates that nonuniformly distributed targets might be involved in these reactions. Calcium was released from intracellular stores as indicated by experiments performed in Ca(2+)-free buffer. L-type Ca(2+)-channel blocker diltiazem (100 mumol/L) was not able to block these responses. NO.-induced Ca2+ release from intracellular stores caused capacitative Ca2+ entry. Both thapsigargin (1 mumol/L) and cyclopiazonic acid (10 mumol/L) inhibited the SNP response completely, whereas neither ryanodine (up to 100 mumol/L) nor dantrolene (100 mumol/L) was able to inhibit Ca2+ changes induced by SNP, indicating that primarily inositol 1,4,5-triphosphate (IP3)-dependent stores are released upon stimulation with NO.. A small inhibitory effect of ATP- and SNP-induced peak [Ca2+]i increase was measured in the presence of both caffeine (20 mmol/L) and procaine (1 mmol/L). Evidence is presented that cGMP is not involved in NO.-induced Ca2+ signals, as neither inhibitors of guanylate cyclase (methylene blue and LY 83583) nor cell permeant analogues of cGMP altered or simulated [Ca2+] changes. An inhibitor of cGMP-dependent protein kinase was also ineffective. We therefore propose that endothelial cells have specific targets proximal or at IP3 receptors to induce Ca2+ changes in endothelial cells stimulated with NO..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Caffeine / pharmacology
  • Calcium / metabolism*
  • Cell Line
  • Cyclic GMP / metabolism*
  • Dantrolene / pharmacology
  • Diltiazem / pharmacology
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism*
  • Enzyme Activation
  • Guanylate Cyclase / metabolism
  • Humans
  • Indoles / pharmacology
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Nitric Oxide / pharmacology*
  • Nitroprusside / pharmacology
  • Penicillamine / analogs & derivatives
  • Penicillamine / pharmacology
  • Procaine / pharmacology
  • Ryanodine / pharmacology
  • S-Nitroso-N-Acetylpenicillamine
  • Thapsigargin / pharmacology

Substances

  • Indoles
  • Ryanodine
  • Nitroprusside
  • Nitric Oxide
  • Caffeine
  • Procaine
  • Thapsigargin
  • S-Nitroso-N-Acetylpenicillamine
  • Inositol 1,4,5-Trisphosphate
  • Adenosine Triphosphate
  • Guanylate Cyclase
  • Diltiazem
  • Dantrolene
  • Penicillamine
  • Cyclic GMP
  • Calcium
  • cyclopiazonic acid