Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.5 (thrombin)
 33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intravascular EDRF-NO production is known to be impaired in some diseases, e.g., diabetes. This phenomenon may also contribute to the development of diabetic vascular disease. More recently the presence of NO synthase (ecNOS, iNOS) have been recognized in human platelets. Platelets produce NO only during activation, even though in minute amounts. This platelet derived NO seems to play an important physiological role, as it inhibits further platelet recruitment quite substantially. In the present report washed platelets isolated from healthy persons and patients with chronic myeloproliferative diseases (CMPD) were exposed to common and physiologically relevant activators (i.e., thrombin, collagen, epinephrine etc.). These tests were carried out in 20 healthy volunteers and 15 patients suffering from myeloproliferative disorders associated with thrombocytosis. As a consequence of pathological platelet function observed in CMPD, the in vitro platelet NO response is impaired in the patient group. One may assume, that reduced platelet NO response, at least in part, may contribute to platelet hyperfunction, angiopathy and thrombotic complications in some cases of CMPD.
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PMID:Effects of in vitro platelet activation on platelet derived nitric oxide production in healthy humans and in chronic myeloproliferative diseases with elevated platelet counts. 1452 61

Adhesion molecules such as P-selectin (CD 62), glycoprotein (CP) 53 (CD63) and thrombospondin play a decisive role in the thrombogenic transformation of platelets. Here we present evidence obtained using flow cytometric analysis that the PGI(2)-mimetics iloprost and taprostene, and an NO (EDRF)donor (SIN-1) are able to inhibit the expression of P-selectin, GP 53 and thrombospondin on human platelets activated by submaximal concentrations of thrombin. Since the half-maximal concentrations for inhibition of antigen expression (0.15 nM for iloprost, 3.0-5.3 nM for taprostene) are much lower than for activation of adenylate cyclase (1.4 nM for iloprost and 29.4 nM for taprostene) our data suggest that the occupation of a small number of PGI(2)-receptors is sufficient to inhibit the thrombogenic transformation and that spare PGI(2)-receptors are present on human platelets. In diabetes, the EC(50) for inhibition of expression of platelet antigens is shifted to higher concentrations suggesting that platelets from type 1 diabetic patients are partly resistant to PGI(2). Since the dose dependent increase in c-AMP by iloprost is not changed and intraplatelet c-AMP is elevated in platelets of diabetic patients, we assume that steps in the activation cascade subsequent to activation of adenylate cyclase are disturbed in diabetes.
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PMID:Expression of Adhesion Molecules on the Surface of Activated Platelets is Diminished by PGI(2)-analogues and an NO (EDRF)-Donor: A Comparison Between Platelets of Healthy and Diabetic Subjects. 2104 43


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