Antiplatelet properties of protein S-nitrosothiols derived from nitric oxide and endothelium-derived relaxing factor.
S-nitrosothiols may serve as carriers in the mechanism of action of endothelium-derived relaxing factor (EDRF) by stabilizing the labile nitric oxide (NO) radical from inactivation by reactive species in the physiological milieu and by delivering NO to the heme activator site of guanylyl cyclase. Low-molecular-weight thiols, such as cysteine and glutathione, form S-nitrosothiol adducts with vasodilatory and antiplatelet properties, and protein thiols can interact in the presence of NO and/or EDRF to form uniquely stable S-nitroso-proteins. We now show that the S-nitroso-proteins, S-nitroso-albumin, S-nitroso-tissue type plasminogen activator, and S-nitroso-cathepsin B, have potent antiplatelet effects with an IC50 of approximately 1.5 microM. In the dog, S-nitroso-albumin inhibits ex vivo platelet aggregation and significantly prolongs the template bleeding time from 2.15 +/- 0.13 (mean +/- SEM) to 9.70 +/- 1.24 minutes. The antiplatelet action of S-nitroso-proteins is associated with the stimulation of guanylyl cyclase and a significant decrease in fibrinogen binding to platelets. S-Nitroso-proteins undergo thiol-nitrosothiol exchange with low-molecular-weight thiols to form low-molecular-weight S-nitroso-thiols, and they also interact directly with the platelet surface, both of which processes facilitate generation of NO. These data suggest that S-nitroso-proteins are potent antiplatelet agents and may be intermediates in the antiplatelet mechanism of EDRF action.
Department of Medicine, Harvard University, Boston.
D I
DI
Simon
J S
JS
Stamler
O
O
Jaraki
J F
JF
Keaney
J A
JA
Osborne
S A
SA
Francis
D J
DJ
Singel
J
J
Loscalzo
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001760:Bleeding Time; D001777:Blood Coagulation / Q000187:drug effects; D001792:Blood Platelets / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D001798:Blood Proteins / Q000494:pharmacology*; D003094:Collagen / Q000494:pharmacology; D006152:Cyclic GMP / Q000097:blood; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D004285:Dogs; D005340:Fibrinogen / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D009603:Nitroso Compounds / Q000737:chemistry / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D026422:S-Nitrosoglutathione; D026403:S-Nitrosothiols; D013997:Time Factors
D001798:Blood Proteins; D009603:Nitroso Compounds; D010975:Platelet Aggregation Inhibitors; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D000244:Adenosine Diphosphate; D005340:Fibrinogen; D003094:Collagen; C021315:S-nitrosocysteine; D005978:Glutathione; D006152:Cyclic GMP; D003545:Cysteine