Cell surface thiol isomerases may explain the platelet-selective action of S-nitrosoglutathione

• Published in: Nitric oxide 2011-10, Vol.25 (3), p.303-308
• Main Authors: Xiao, Fang, Gordge, Michael P.
• Format: Article
• Language: English
• Subjects: Blood Platelets - metabolism; Cells, Cultured; Coronary Vessels - cytology; Coronary Vessels - enzymology; Endothelial cells; Endothelial Cells - enzymology; Endothelial Cells - metabolism; Flow Cytometry; Humans; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - enzymology; Platelets; Protein Disulfide-Isomerases - metabolism; Protein disulphide isomerase (PDI); Reference Values; S-nitrosoglutathione (GSNO); S-Nitrosoglutathione - metabolism; Smooth muscle cells; Sulfhydryl Compounds - metabolism; Thiol isomerases
• ISSN: 1089-8603; 1089-8611
• DOI: 10.1016/j.niox.2011.05.008

S-nitrosoglutathione (GSNO) at low concentration inhibits platelet aggregation without causing vasodilation, suggesting platelet-selective nitric oxide delivery. The mechanism of this selectivity is unknown, but may involve cell surface thiol isomerases, in particular protein disulphide isomerase (csPDI) (EC 5.3.4.1). We have now compared csPDI expression and activity on platelets, endothelial cells and vascular smooth muscle cells, and the dependence on thiol reductase activity of these cell types for NO uptake from GSNO. csPDI expression was measured by flow cytometry and its reductase activity using the pseudosubstrate dieosin glutathione disulphide. This activity assay was adapted and validated for 96-well plate format. Flow cytometry revealed csPDI on all three cell types, but percentage positivity of expression was higher on platelets than on vascular cells. Consistent with this, thiol isomerase-related reductase activity was higher on platelets (P