Peroxynitrite modulates receptor-activated Ca2+ signaling in vascular endothelial cells.
Peroxynitrite (ONOO-) is formed from superoxide (O2-) and .NO. We have previously reported that O2- does not alter endothelial cell Ca2+ signaling. To test whether .NO alters Ca2+ signaling, cells were incubated with the .NO donor, spermine NONOate. Neither spermine NONOate nor S-nitroso-N-acetyl penicillamine (SNAP) altered bradykinin-stimulated Ca2+ signaling. By contrast, 3-morpholinosydnonimine (SIN-1), which generates ONOO- by releasing O2- and .NO essentially in a simultaneous manner, significantly inhibited signaling. Initially, the inhibitory effect of 1 mM SIN-1 was selective toward agonist-stimulated influx of external Ca2+. At later time points, SIN-1 additionally depleted internal stores of releasable Ca2+. When cells were coincubated with SIN-1 plus superoxide dismutase, a technique designed to scavenge O2- and convert SIN-1 to purely an .NO-donor compound, Ca2+ signaling was identical to control. SIN-1C, the inactive metabolite of SIN-1, had no effect on [Ca2+]i. This study demonstrates that exogenously generated ONOO- modulates endothelial cell Ca2+ signaling, suggesting that ONOO- is of biological relevance to vasoregulation.
Elliott
S J
SJ
Department of Pediatrics, Medical College of Wisconsin, Milwaukee 53226, USA. elliott@mcw.edu
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000819:agonists / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009566:Nitrates / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects*
D009566:Nitrates; D011956:Receptors, Cell Surface; C039642:peroxynitric acid; D009569:Nitric Oxide; C002385:linsidomine; D015544:Inositol 1,4,5-Trisphosphate; D008981:Molsidomine; D001920:Bradykinin; D002118:Calcium