Evidence for the presence of L-arginine-nitric oxide pathway in human red blood cells: relevance in the effects of red blood cells on platelet function.
There is a renewed interest in the role of red blood cells (RBCs) in the regulation of vascular tone and platelet homeostasis. To examine whether human RBCs synthesize NO from L-arginine, which may mediate the antiplatelet effects of these cells, purified RBCs (10(7)-10(8)/ml) were incubated with [3H]L-arginine, and its conversion into [3H]L-citrulline determined. RBCs consistently converted [3H]L-arginine to [3H]L-citrulline in a Ca2+-dependent fashion, and this conversion was inhibited by two different specific NO synthase inhibitors. Suspension of RBCs (10(7)-10(8)/ml) reduced platelet aggregation, and the RBC-mediated inhibition of platelet aggregation was blocked by pretreatment of RBCs with NO synthase inhibitor and potentiated by pretreatment with superoxide dismutase. Release of serotonin by aggregating platelets also was inhibited in the presence of RBCs. Western analysis with a specific mouse monoclonal antibody provided direct evidence for the presence of human endothelium-type constitutive NO synthase with a molecular mass approximately 140 kDa in the RBC cytosol. These observations suggest that RBCs possess endothelium-type NO synthase and may regulate platelet function at least in part by in situ release of NO.
Chen
L Y
LY
Department of Medicine, College of Medicine, University of Florida, and the VA Medical Center, Gainesville 32610-0277, USA.
Mehta
J L
JL
D000818:Animals; D001120:Arginine / Q000097:blood*; D001792:Blood Platelets / Q000502:physiology*; D015153:Blotting, Western; D002956:Citrulline / Q000097:blood; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism* / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000097:blood; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010974:Platelet Aggregation / Q000502:physiology; D012701:Serotonin / Q000097:blood
D004791:Enzyme Inhibitors; D002956:Citrulline; D009569:Nitric Oxide; D012701:Serotonin; D001120:Arginine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D019331:NG-Nitroarginine Methyl Ester