TY - JOUR
T1 - L-Arginine Depletion in Preeclampsia Orients Nitric Oxide Synthase Toward Oxidant Species
AU - Noris, Marina
AU - Todeschini, Marta
AU - Cassis, Paola
AU - Pasta, Fabio
AU - Cappellini, Anna
AU - Bonazzola, Samantha
AU - Macconi, Daniela
AU - Maucci, Raffaella
AU - Porrati, Francesca
AU - Benigni, Ariela
AU - Picciolo, Claudio
AU - Remuzzi, Giuseppe
PY - 2004/3
Y1 - 2004/3
N2 - Less nitric oxide (NO)-dependent vasodilation and excess formation of reactive oxygen species could explain poor placenta perfusion in preeclampsia, but the pathways involved are unknown. We tested the hypothesis that reduced NO activity and increased oxidative stress in preeclamptic placenta is related to a low bioavailability of L-arginine. Placental endothelial NO synthase (ecNOS) expression (by immunoperoxidase) and activity (by diaphorase and [ 3H]L-citrulline formation) were comparable in normotensive pregnancy and in preeclampsia, whereas nitrotyrosine staining, a marker of peroxynitrite, was stronger in preeclamptic villi, confirming previously reported data. Oxidative tissue damage was documented in preeclamptic villi by strong 4-hydroxynonenal-lysine staining (by immunoperoxidase), which closely colocalized with nitrotyrosine. Concentration of the NO precursor L-arginine (by HPLC) in umbilical blood and in villous tissue was lower in preeclampsia than in normotensive pregnancy. This was not caused by a defective L-arginine transport, because gene expression of the CAT-1, 4F2hc, and LAT-1 cationic amino acid transporters (by real-time reverse-transcription polymerase chain reaction [RT-PCR]) was normal. Instead, gene expression (by real-time RT-PCR) and protein tissue content (by immunoperoxidase and Western blot) of arginase II-the enzyme that degrades arginine to ornithine-were higher in preeclamptic villi than in normotensive pregnancy. These results provide a biochemical explanation for defective NO activity and increased oxidative stress in preeclamptic placenta. In normal placenta, adequate concentration of L-arginine orients ecNOS toward NO. In preeclampsia, a lower than normal L-arginine concentration caused by arginase II overexpression redirects ecNOS toward peroxynitrite.
AB - Less nitric oxide (NO)-dependent vasodilation and excess formation of reactive oxygen species could explain poor placenta perfusion in preeclampsia, but the pathways involved are unknown. We tested the hypothesis that reduced NO activity and increased oxidative stress in preeclamptic placenta is related to a low bioavailability of L-arginine. Placental endothelial NO synthase (ecNOS) expression (by immunoperoxidase) and activity (by diaphorase and [ 3H]L-citrulline formation) were comparable in normotensive pregnancy and in preeclampsia, whereas nitrotyrosine staining, a marker of peroxynitrite, was stronger in preeclamptic villi, confirming previously reported data. Oxidative tissue damage was documented in preeclamptic villi by strong 4-hydroxynonenal-lysine staining (by immunoperoxidase), which closely colocalized with nitrotyrosine. Concentration of the NO precursor L-arginine (by HPLC) in umbilical blood and in villous tissue was lower in preeclampsia than in normotensive pregnancy. This was not caused by a defective L-arginine transport, because gene expression of the CAT-1, 4F2hc, and LAT-1 cationic amino acid transporters (by real-time reverse-transcription polymerase chain reaction [RT-PCR]) was normal. Instead, gene expression (by real-time RT-PCR) and protein tissue content (by immunoperoxidase and Western blot) of arginase II-the enzyme that degrades arginine to ornithine-were higher in preeclamptic villi than in normotensive pregnancy. These results provide a biochemical explanation for defective NO activity and increased oxidative stress in preeclamptic placenta. In normal placenta, adequate concentration of L-arginine orients ecNOS toward NO. In preeclampsia, a lower than normal L-arginine concentration caused by arginase II overexpression redirects ecNOS toward peroxynitrite.
KW - Arginine
KW - Nitric oxide synthase
KW - Nitrites
KW - Oxidative stress
KW - Preeclampsia
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U2 - 10.1161/01.HYP.0000116220.39793.c9
DO - 10.1161/01.HYP.0000116220.39793.c9
M3 - Article
C2 - 14744923
AN - SCOPUS:10744232765
VL - 43
SP - 614
EP - 622
JO - Hypertension
JF - Hypertension
SN - 0194-911X
IS - 3
ER -