Nitric oxide scavenging by red cell microparticles.
Red cell microparticles form during the storage of red blood cells and in diseases associated with red cell breakdown and asplenia, including hemolytic anemias such as sickle cell disease. These small phospholipid vesicles that are derived from red blood cells have been implicated in the pathogenesis of transfusion of aged stored blood and hemolytic diseases, via activation of the hemostatic system and effects on nitric oxide (NO) bioavailability. Red cell microparticles react with the important signaling molecule NO almost as fast as cell-free hemoglobin, about 1000 times faster than red-cell-encapsulated hemoglobin. The degree to which this fast reaction with NO by red cell microparticles influences NO bioavailability depends on several factors that are explored here. In the context of stored blood preserved in ADSOL, we find that both cell-free hemoglobin and red cell microparticles increase as a function of duration of storage, and the proportion of extra erythrocytic hemoglobin in the red cell microparticle fraction is about 20% throughout storage. Normalized by hemoglobin concentration, the NO-scavenging ability of cell-free hemoglobin is slightly higher than that of red cell microparticles as determined by a chemiluminescence NO-scavenging assay. Computational simulations show that the degree to which red cell microparticles scavenge NO will depend substantially on whether they enter the cell-free zone next to the endothelial cells. Single-microvessel myography experiments performed under laminar flow conditions demonstrate that microparticles significantly enter the cell-free zone and inhibit acetylcholine, endothelial-dependent, and NO-dependent vasodilation. Taken together, these data suggest that as little as 5 μM hemoglobin in red cell microparticles, an amount formed after the infusion of one unit of aged stored packed red blood cells, has the potential to reduce NO bioavailability and impair endothelial-dependent vasodilation.
Department of Physics, Wake Forest University, Winston-Salem, NC 27109, USA.
Chen
C
Liu
Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27101, USA.
Weixin
W
Zhao
Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27101, USA.
George J
GJ
Christ
Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Mark T
MT
Gladwin
Department of Physics, Wake Forest University, Winston-Salem, NC 27109, USA. Electronic address: shapiro@wfu.edu.
Daniel B
DB
Kim-Shapiro
D000109:Acetylcholine; D000225:Adenine / Q000494:pharmacology; D001682:Biological Availability; D001803:Blood Transfusion; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D018680:Cholinergic Antagonists; D042783:Endothelial Cells / Q000378:metabolism*; D045462:Endothelium-Dependent Relaxing Factors / Q000737:chemistry; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D008353:Mannitol / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood / Q000737:chemistry*; D010108:Oxyhemoglobins / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology; D014664:Vasodilation / Q000502:physiology
C037839:ADSOL; D018680:Cholinergic Antagonists; D045462:Endothelium-Dependent Relaxing Factors; D006454:Hemoglobins; D010108:Oxyhemoglobins; D009569:Nitric Oxide; D008353:Mannitol; D012965:Sodium Chloride; D005947:Glucose; D000225:Adenine; D000109:Acetylcholine
ACD; ACh; Blood storage; CFZ; Cell-free hemoglobin; EDRF; Free radicals; Hb; Hct; MP; Nitric oxide; OxyHb; PE; RBC; Red cell microparticles; acetylcholine; acid citrate dextrose; cell-free zone; endothelial-derived relaxing factor; hematocrit; hemoglobin; microparticle; oxygenated hemoglobin; phenylephrine; red blood cell