Fibrinogen effects on erythrocyte nitric oxide mobilization in presence of acetylcholine.
OBJECTIVE
The objectives of this study were to evaluate the effects of high fibrinogen concentration on erythrocyte deformability on mobilization of nitric oxide (NO) and of its metabolites in the presence of acetylcholine (ACh) in healthy human blood samples.


METHODS
Levels of NO were evaluated by amperometric method. Nitrite, nitrate and S-nitrosoglutathione (GSNO) were measured using the spectrophotometric Griess reaction. Erythrocyte deformability was determined using the Rheodyn SSD laser diffractometer.


RESULTS
In the presence of high concentrations of fibrinogen and ACh (10 μM) in the blood samples from healthy humans the erythrocyte nitrites, nitrates and GSNO concentrations increased without significant changes in NO efflux. Mobilization of NO in erythrocytes' presence was enhanced in the presence of ACh and high fibrinogen levels.


CONCLUSIONS
These results suggest that during inflammation when both ACh and high levels of fibrinogen are present, NO delivery by erythrocytes might be compromised by their NO scavenging ability that acts as a compensatory mechanism against the overproduced NO by endothelial inducible nitric oxide synthase.
Institute of Biochemistry, Institute of Molecular Medicine, Faculty of Medicine University of Lisbon, Portugal. carlotasaldanha@fm.ul.pt
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C
Saldanha
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Freitas
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JP
Almeida
D000109:Acetylcholine / Q000097:blood / Q000378:metabolism*; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000378:metabolism
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005340:Fibrinogen; D000109:Acetylcholine