The arachidonic acid effect on platelet nitric oxide level.
Arachidonic acid can act as a second messenger regulating many cellular processes among which is nitric oxide (NO) formation. The aim of the present study was to investigate the molecular mechanisms involved in the arachidonic acid effect on platelet NO level. Thus NO, cGMP and superoxide anion level, the phosphorylation status of nitric oxide synthase, the protein kinase C (PKC), and NADPH oxidase activation were measured. Arachidonic acid dose-dependently reduced NO and cGMP level. The thromboxane A(2) mimetic U46619 behaved in a similar way. The arachidonic acid or U46619 effect on NO concentration was abolished by the inhibitor of the thromboxane A(2) receptor SQ29548 and partially reversed by the PKC inhibitor GF109203X or by the phospholipase C pathway inhibitor U73122. Moreover, it was shown that arachidonic acid activated PKC and decreased nitric oxide synthase (eNOS) activities. The phosphorylation of the inhibiting eNOSthr495 residue mediated by PKC was increased by arachidonic acid, while no changes at the activating ser1177 residue were shown. Finally, arachidonic acid induced NADPH oxidase activation and superoxide anion formation. These effects were greatly reduced by GF109203X, U73122, and apocynin. Likely arachidonic acid reducing NO bioavailability through all these mechanisms could potentiate its platelet aggregating power.
Signorello
Maria Grazia
MG
Department of Experimental Medicine, Biochemistry Section, University of Genoa, Viale Benedetto XV 1, 16132 Genova, Italy.
Segantin
Alessia
A
Leoncini
Giuliana
G
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D006152:Cyclic GMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D019255:NADPH Oxidases / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism
D009566:Nitrates; D009573:Nitrites; D013481:Superoxides; D010769:Phosphothreonine; D016718:Arachidonic Acid; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; D011493:Protein Kinase C; D006152:Cyclic GMP; D002118:Calcium