Ethanol inhibits L-arginine uptake and enhances NO formation in human placenta.
The acute effects of ethanol (20-60 mM) on L-arginine uptake and nitric oxide (NO) formation was investigated in human placental cotyledons perfused at constant flow. Ethanol (40 mM) decreased L-[3H]arginine uptake from 27.6 +/- 2.3 to 15.8 +/- 1.3 per cent (P < 0.05) of the injected dose and significantly enhanced NO levels in the perfusate from 0.88 +/- 0.11 to 2.80 +/- 0.39 microM. Ethanol also elicited the constriction of placental vessels. The effects of ethanol (20-60 mM) on L-arginine uptake and endothelial NO synthase (eNOS) activity were also investigated in cultured human umbilical vein endothelial cells (HUVEC). After 60 min of ethanol (40 mM) exposure, basal L-[3H]arginine uptake (4.7 +/- 0.3 pmol/microg protein/min) was inhibited by 60 per cent (P < 0.05). Basal eNOS activity in HUVEC determined under "no flow" (static) conditions was significantly increased (approximately 1.8 fold) by 60 mM ethanol. These data are consistent with a stimulatory effect of ethanol on eNOS activity in both basal and flow-stimulated conditions, which may serve a protective role against its vasoconstrictive acute effect. While acute ethanol administration inhibits L-arginine uptake, the present results do not allow us to speculate on the effects of chronic ethanol exposure on NO formation in the fetoplacental unity.
Acevedo
C G
CG
Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile. cacevedo@udec.cl
Carrasco
G
G
Burotto
M
M
Rojas
S
S
Bravo
I
I
D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D014316:Tritium; D014471:Umbilical Veins
D014316:Tritium; D009569:Nitric Oxide; D000431:Ethanol; D006632:Histamine; D001120:Arginine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D019331:NG-Nitroarginine Methyl Ester