Human red blood cells at work: Identification and visualization of erythrocytic eNOS activity in health and disease

Miriam M. Cortese-Krott, Ana Rodriguez-Mateos, Roberto Sansone, Gunter G C Kuhnle, Sivatharsini Thasian-Sivarajah, Thomas Krenz, Patrick Horn, Christoph Krisp, Dirk Wolters, Christian Heiß, Klaus Dietrich Kröncke, Neil Hogg, Martin Feelisch, Malte Kelm*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

142 Citations (Scopus)


A nitric oxide synthase (NOS)-like activity has been demonstrated in human red blood cells (RBCs), but doubts about its functional significance, isoform identity and disease relevance remain. Using flow cytometry in combination with the nitric oxide (NO)-imaging probe DAF-FM we find that all blood cells form NO intracellularly, with a rank order of monocytes > neutrophils > lymphocytes > RBCs > platelets. The observation of a NO-related fluorescence within RBCs was unexpected given the abundance of the NO-scavenger oxyhemoglobin. Constitutive normoxic NO formation was abolished by NOS inhibition and intracellular NO scavenging, confirmed by laser-scanning microscopy and unequivocally validated by detection of the DAF-FM reaction product with NO using HPLC and LC-MS/MS. Using immunoprecipitation, ESI-MS/MS-based peptide sequencing and enzymatic assay we further demonstrate that human RBCs contain an endothelial NOS (eNOS) that converts L- 3H-arginine to L-3H-citrulline in a Ca2+/calmodul- independent fashion. Moreover, in patients with coronary artery disease, red cell eNOS expression and activity are both lower than in age-matched healthy individuals and correlate with the degree of endothelial dysfunction. Thus, human RBCs constitutively produce NO under normoxic conditions via an active eNOS isoform, the activity of which is compromised in patients with coronary artery disease.

Original languageEnglish
Pages (from-to)4229-4237
Number of pages9
Issue number20
Publication statusPublished - 15 Nov 2012
Externally publishedYes


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