title: Direct measurement of nitric oxide production in platelets: relationship with cytosolic Ca2+ concentration.
abstract: NO production in platelets has been followed by electrochemical detection. It was undetectable in unstimulated platelets and in thrombin or ADP-stimulated platelets, but dose-dependently stimulated by collagen. A production of 5 10(-19) mol/platelet was reached with 9 micrograms collagen. In collagen-stimulated platelets, preincubation with 1 mM L-Arg, D-Arg or L-NMMA increased by 77%, left unchanged or decreased by 63% NO production, respectively. NO production did not parallel cytosolic Ca2+ changes, although it decreased in low Ca2+ medium or when Ca2+ transients were attenuated by intracellular Ca2+ buffer. These results confirm that human platelets can generate NO. They demonstrate that cytosolic [Ca2+], although participating in the regulation of its synthesis, is not the messenger for NO synthase activation. Platelet NO production could become functionally important when collagen fibrils of the sub-endothelium are accessible.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009569:Nitric Oxide / Q000032:analysis / Q000037:antagonists & inhibitors / Q000097:blood*; D011199:Potentiometry / Q000379:methods; D013237:Stereoisomerism; D013917:Thrombin / Q000494:pharmacology; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000244:Adenosine Diphosphate; D001120:Arginine; D013917:Thrombin; D002118:Calcium