title: Differentiation of cGMP-dependent and -independent nitric oxide effects on platelet apoptosis and reactive oxygen species production using platelets lacking soluble guanylyl cyclase.
abstract: Platelet activation is an irreversible process resulting in platelet apoptosis and necrosis, and circulating platelets contain many components of the apoptotic machinery. Cyclic guanosine monophosphate (cGMP) generated by nitric oxide (NO) activated soluble guanylyl cyclase (sGC) plays a crucial role in preventing platelet activation. However, in addition to activation of sGC, cGMP-independent NO effects in platelets have been described. To differentiate between cGMP-dependent and -independent NO effects on platelet apoptosis and reactive oxygen species (ROS) production, we generated platelet-specific sGC-deficient mice (PS-GCKO). Platelet apoptosis was induced by a combination of thrombin/convulxin (Thr/Cvx) and assessed by phosphatidylserine (PS) surface exposure, and loss of the mitochondrial membrane potential. NO-induced inhibition of PS externalisation was mediated only by cGMP-dependent mechanisms. Inhibition of the mitochondrial membrane potential decrease at low NO concentration was also cGMP-dependent but became cGMP-independent at high NO concentrations. In contrast, inhibition of ROS formation at any NO concentration was mediated by cGMP-independent mechanisms, very likely due to direct radical scavenging. NO inhibits platelet apoptosis by cGMP-dependent mechanisms and ROS production by cGMP-independent mechanisms. The PS-GCKO mouse model is an important tool for the differentiation of cGMP-dependent and -independent NO effects on platelets.
authors.affiliation: Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Würzburg, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Rukoyatkina
authors.forename: U
authors.initials: U
authors.lastname: Walter
authors.forename: A
authors.initials: A
authors.lastname: Friebe
authors.forename: S
authors.initials: S
authors.lastname: Gambaryan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D003435:Crotalid Venoms / Q000494:pharmacology; D006152:Cyclic GMP / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000172:deficiency* / Q000235:genetics; D006801:Humans; D037181:Lectins, C-Type; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000097:blood*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010718:Phosphatidylserines / Q000097:blood; D015539:Platelet Activation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000097:blood*; D018160:Receptors, Cytoplasmic and Nuclear / Q000172:deficiency* / Q000235:genetics; D015398:Signal Transduction; D000071756:Soluble Guanylyl Cyclase; D013917:Thrombin / Q000378:metabolism; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D003435:Crotalid Venoms; D004791:Enzyme Inhibitors; D037181:Lectins, C-Type; D020030:Nitric Oxide Donors; D010718:Phosphatidylserines; D017382:Reactive Oxygen Species; D018160:Receptors, Cytoplasmic and Nuclear; D014475:Uncoupling Agents; D009569:Nitric Oxide; C028890:convulxin; D013917:Thrombin; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D006152:Cyclic GMP