Format

Send to

Choose Destination
J Biol Chem. 2015 Jan 9;290(2):1281-94. doi: 10.1074/jbc.M114.609222. Epub 2014 Dec 3.

Mechanisms of human erythrocytic bioactivation of nitrite.

Author information

1
From the Department of Physics and.
2
From the Department of Physics and the Translational Science Center Wake Forest University, Winston-Salem, North Carolina 27109, the Departments of Radiology and.
3
Physics Department, University of Richmond, Richmond, Virgina 23173.
4
the Translational Science Center Wake Forest University, Winston-Salem, North Carolina 27109, Hypertension and Vascular Research Center and.
5
the Translational Science Center Wake Forest University, Winston-Salem, North Carolina 27109, the Departments of Radiology and Biomedical Engineering and.
6
Pathology-Comparative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, and.
7
Heart, Lung, Blood, and Vascular Medicine Institute and.
8
Heart, Lung, Blood, and Vascular Medicine Institute and the Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.
9
From the Department of Physics and the Translational Science Center Wake Forest University, Winston-Salem, North Carolina 27109, Hypertension and Vascular Research Center and Biomedical Engineering and shapiro@wfu.edu.

Abstract

Nitrite signaling likely occurs through its reduction to nitric oxide (NO). Several reports support a role of erythrocytes and hemoglobin in nitrite reduction, but this remains controversial, and alternative reductive pathways have been proposed. In this work we determined whether the primary human erythrocytic nitrite reductase is hemoglobin as opposed to other erythrocytic proteins that have been suggested to be the major source of nitrite reduction. We employed several different assays to determine NO production from nitrite in erythrocytes including electron paramagnetic resonance detection of nitrosyl hemoglobin, chemiluminescent detection of NO, and inhibition of platelet activation and aggregation. Our studies show that NO is formed by red blood cells and inhibits platelet activation. Nitric oxide formation and signaling can be recapitulated with isolated deoxyhemoglobin. Importantly, there is limited NO production from erythrocytic xanthine oxidoreductase and nitric-oxide synthase. Under certain conditions we find dorzolamide (an inhibitor of carbonic anhydrase) results in diminished nitrite bioactivation, but the role of carbonic anhydrase is abrogated when physiological concentrations of CO2 are present. Importantly, carbon monoxide, which inhibits hemoglobin function as a nitrite reductase, abolishes nitrite bioactivation. Overall our data suggest that deoxyhemoglobin is the primary erythrocytic nitrite reductase operating under physiological conditions and accounts for nitrite-mediated NO signaling in blood.

KEYWORDS:

Erythrocyte; Hemoglobin; Nitric Oxide; Nitrite; Platelet; Redox Signaling; Spectroscopy

PMID:
25471374
PMCID:
PMC4294492
DOI:
10.1074/jbc.M114.609222
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center