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

Calcium phosphate precipitation and retrovirus-mediated infection methods were used to stably infect bovine pulmonary artery endothelial cells (BPAECs) with mammalian expression vectors bearing human prepro-ET-1 cDNA. The calcium phosphate precipitation method afforded a stably transfected cell line that expressed approximately four times higher ET-1 than untransfected BPAEC by radioimmunoassay and at the mRNA level. The retrovirus-mediated transfection method yielded stably infected clones that secreted eightfold to 10-fold higher ET-1 than the nontransfected BPAECs; one clone continued to produce 10-fold higher levels after continuous assay for 1 year. Both transfected and nontransfected cells showed an increase (approximately twofold) in ET-1 production in response to thrombin (10 U/ml). Downregulation of ET-1 production was exhibited by both transfected and nontransfected cells in response to nitric oxide (NO) donors: sodium nitroprusside (NOPr), S-nitroso-N-acetoxy penicillamine (SNAP), and acetoxime. The potentiation of NO by superoxide dismutase (SOD) also downregulated ET-1 production. These studies show that an exogenous gene introduced into a cell type that normally expresses that gene product can be regulated by agonists and antagonists in a manner similar to the normal gene regulatory mechanisms for that cell type. This is of potential importance in gene therapy experiments, where mechanisms for regulation of expression remain elusive.
J Cardiovasc Pharmacol 1993
PMID:Regulation of endothelin-1 expression in normal and transfected endothelial cells. 750 93

Heparin shows a blood pressure-lowering effect in various hypertensive rat models. This study was designed to examine the effect of heparin on vasoconstrictor endothelin-1 (ET-1) production by cultured human umbilical vein endothelial cells (HUVECs). ET-1 and cyclic GMP levels in the medium were determined by radioimmunoassay. ET-1 mRNA was quantified by densitometric Northern blot analysis. ET-1 was released into the medium in a time-dependent manner, and its release was augmented by thrombin (10 U/ml). Heparin suppressed both basal and thrombin-stimulated ET-1 secretion and its mRNA expression in a dose-dependent manner. Heparin suppressed ET-1 mRNA expression in a time-dependent fashion. Heparin did not suppress both basal and thrombin-stimulated ET-1 production in the presence of NG-monomethyl-L-arginine (L-NMMA) (10(-5) M). The production of cGMP stimulated by thrombin was significantly enhanced by heparin, but not in the presence of L-NMMA (10(-5) M). Heparin may suppress vasoconstrictor ET-1 production mediated by the enhancement of endothelium-derived nitric oxide in HUVECs.
J Cardiovasc Pharmacol 1993
PMID:Effect of heparin on endothelin-1 production by cultured human endothelial cells. 750 96

We studied the inhibitory effects of heparin, thrombin inhibitor, and protein kinase C (PKC) inhibitor on basal and thrombin-induced preproendothelin-1 (prepro-ET-1) and proto-oncogene c-fos mRNA expression in cultured bovine endothelial cells (ECs). Northern blot analysis using cDNA for bovine prepro-ET-1 as a probe showed that heparin lowered not only the basal but also the stimulated expression of prepro-ET-1 mRNA by thrombin. A selective thrombin inhibitor (argatroban) and a PKC inhibitor (staurosporine) also inhibited thrombin-induced but not basal prepro-ET-1 mRNA expression. Heparin similarly inhibited thrombin-induced c-fos proto-oncogene mRNA expression in ECs. These data suggest that heparin, in addition to its antithrombin effect, has an inhibitory effect on prepro-ET-1 mRNA expression, possibly via a PKC-dependent pathway.
J Cardiovasc Pharmacol 1993
PMID:Heparin inhibits endothelin-1 and proto-oncogene c-fos gene expression in cultured bovine endothelial cells. 750 97

Thirty consecutive children scheduled for pediatric cardiac operation with cardiopulmonary bypass were included in the study. Before the operation, the patients were randomly divided into two groups: with aprotinin (n = 15, 30,000 U/kg after induction of anesthesia, 30,000 U/kg added to the prime of the cardiopulmonary bypass or without aprotinin (n = 15). Thrombomodulin, (free) protein S, protein C, and thrombin/antithrombin III complex were measured from arterial blood samples taken after induction of anesthesia (at baseline, before aprotinin) and before, during, and after cardiopulmonary bypass until the first postoperative day. Standard coagulation parameters (antithrombin III, fibrinogen, platelet count, and partial thromboplastin time) were without differences between the groups. Thrombomodulin plasma concentrations were within normal range ( < 40 micrograms/L) and were similar in both groups at baseline. During cardiopulmonary bypass and until 5 hours after cardiopulmonary bypass, however, thrombomodulin plasma levels were significantly lower in the children treated with aprotinin. No further differences were observed on the first postoperative day. Protein C and protein S plasma levels did not differ between the two groups. Thrombin/antithrombin III-complex plasma concentrations increased significantly during cardiopulmonary bypass, however, without showing differences between children with (225 +/- 49 micrograms/L) and without (149 +/- 31 micrograms/L) aprotinin treatment. Blood loss and the need for homologous blood and blood products did not differ significantly between the two groups. We concluded that administration of aprotinin resulted in reduced thrombomodulin plasma levels in pediatric patients undergoing cardiac operation without altering protein C/protein S plasma concentration. The exact role of aprotinin in endothelium-derived coagulation should be further studied.
J Thorac Cardiovasc Surg 1994 May
PMID:Influence of aprotinin on the thrombomodulin/protein C system in pediatric cardiac operations. 751 76

The antiaggregatory properties of trimetazidine were investigated further by analyzing its effects on cytosolic calcium and proton concentrations, well-known regulators of platelet reactivity. Aggregatory responses of washed platelets were assessed by turbidometry, and cytosolic Ca2+ concentration ([Ca2+]i) and pH (pHi) were determined by their respective fluorescent probes: Fura-2 and BCECF. Preincubation with trimetazidine dose-dependently inhibited platelet aggregation induced by 0.05 U/ml thrombin (p < 0.001). At concentrations < or = 1 mM, trimetazidine did not affect the resting [Ca2+]i value but slightly alkalinized the cytosol by 0.05 +/- 0.03 pH units (p < 0.02, n = 11). In platelets stimulated by 0.05 U/ml thrombin, 0.1 mM trimetazidine did not modify pHi variations but decreased [Ca2+]i variations (p < 0.003, n = 16), blunting by 28 +/- 6% the transient peak of [Ca2+]i (p < 0.006) and decreasing by 6 +/- 2% the equilibrium value (p < 0.005). These inhibitory effects were inversely dependent on thrombin concentrations (p < 0.004, n = 21) and were abolished in the virtual absence of external Ca2+. Trimetazidine therefore attenuates the Ca2+ influx evoked by thrombin, thereby limiting Ca2+ accumulation in stimulated platelets. Such a protective effect may participate in the antiaggregatory properties of trimetazidine.
J Cardiovasc Pharmacol 1994 Mar
PMID:Inhibitory effect of trimetazidine on thrombin-induced aggregation and calcium entry into human platelets. 751 83

It is well known that granulocytes increase infarct size after reperfusion of the ischemic myocardium, and that monocytes promote atherogenesis. Those cells are also believed to play a contributory role in pathogenesis of coronary restenosis as response to arterial injury during balloon angioplasty. The adhesion of those leukocytes to the vascular endothelium is a prerequisite for their recruitment and accumulation in the lesion. Inflammatory mediators likely to occur under those conditions, e.g., histamine, thrombin, oxygen-derived free radicals (ODFR), interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, and activated complement factors, induce in a distinct time course the (transient) expression of the leukocyte adhesion molecules P-selectin, E-selectin, intercellular adhesion molecule (ICAM)-1, and vascular cell adhesion molecule (VCAM)-1 on the endothelium. Only VCAM-1 is specific for monocytes; the others mediate the binding and subsequent extravasation of both monocytes and granulocytes. The response to the relevant inflammatory mediators, except for extracellularly produced ODFR, is coupled via specific receptors on the surface of the endothelium to specific signal transduction pathways and, except for P-selectin (early response), is directly dependent on protein synthesis (intermediate and late response). Protein kinase-C-induced phosphorylation of transcription factors is often shown to be involved. Protein synthesis is preceded by increased transcription of mRNA that is regulated in part by the transcription factor NF-kappa B. Indications have been obtained that intracellularly produced ODFR may be involved in the translocation of this transcription factor.(ABSTRACT TRUNCATED AT 250 WORDS)
J Cardiovasc Pharmacol 1993
PMID:Leukocyte adhesion molecules on the vascular endothelium: their role in the pathogenesis of cardiovascular disease and the mechanisms underlying their expression. 752 71

Experiments were designed to study the effects of trandolaprilat on endothelium-dependent responses in isolated blood vessels. Rings of either femoral or left circumflex coronary arteries of the dog or thoracic aortas of normotensive rats were suspended in organ chambers for isometric tension recording. During contractions induced by prostaglandin F2 alpha, trandolaprilat did not cause direct endothelium-dependent or -independent relaxation. However, when given to preparations incubated with angiotensin I or bradykinin, the compound evoked significant endothelium-dependent relaxation. By contrast, trandolaprilat failed to cause any change in tension when given in the presence of acetylcholine (ACh). In rings of femoral arteries, trandolaprilat potentiated the endothelium-dependent relaxation evoked by bradykinin and adenosine diphosphate; it did not modify the endothelium-dependent relaxations induced by ACh, substance P, or thrombin. In rings of femoral arteries without endothelium, trandolaprilat augmented relaxation induced by adenosine diphosphate (ADP) but not by adenosine. In perfused coronary arteries with but not those without endothelium, trandolaprilat caused relaxation in the absence of exogenous bradykinin (or ADP). These experiments suggest that trandolaprilat does not directly release endothelium-derived relaxing factor from the endothelial cells, does not interfere with the ability of the endothelium to release endothelium-derived relaxing factor, augments the endothelium-dependent responses to bradykinin (given exogenously or produced locally) and angiotensin I by direct interaction with converting enzyme, and potentiates the relaxation induced by ADP by augmenting its direct effect on vascular smooth muscle.
J Cardiovasc Pharmacol 1994
PMID:The endothelium and vascular effects of the ACE inhibitor trandolaprilat. 752 94

Aprotinin reduces blood loss after cardiopulmonary bypass, but may sensitize recipients and is expensive. Tranexamic acid, a synthetic antifibrinolytic, has less disadvantages, but opinions differ regarding its efficacy. We studied three groups of patients undergoing cardiopulmonary bypass for coronary disease: recipients of aprotinin (total dose 4.2 x 10(6) kallikrein inhibiting units, n = 14), recipients of tranexamic acid (total dose 20 mg/kg body weight, n = 15), and nonmedicated controls (n = 14) during 24 hours after cardiopulmonary bypass. Compared with controls, aprotinin reduced blood loss, the number of patients requiring transfusions, and the mean number of transfused red cell units (all with p < 0.05), whereas the recipients of tranexamic acid did not differ either from aprotinin recipients or from controls. Aprotinin and tranexamic acid both mitigated the early postoperative reduction of adenosine diphosphate-induced platelet aggregation seen in the controls (p < 0.05). Postoperative increases of plasma concentrations of the prothrombin activation fragment F1 + 2 and the thrombin-antithrombin III complex showed an activation of intravascular coagulation, without any intergroup differences. The balance between concentrations of tissue plasminogen activator and the type 1 plasminogen activator inhibitor disclosed an activation of fibrinolysis, without differences between the groups. The concentrations of D-dimer, a breakdown product of cross-linked fibrin, remained at baseline in the recipients of aprotinin and tranexamic acid but tripled in the controls (p < 0.05). By contrast, the plasma antiplasmin activity was equally depressed in the tranexamic acid and the control groups but decreased less in the recipients of aprotinin (p < 0.05). This discrepancy may reflect the different modes of action of the two agents, which may make aprotinin more efficacious than tranexamic acid in the "nonfibrinolytic" act of protecting platelet function against attack by plasmin during cardiopulmonary bypass.
J Thorac Cardiovasc Surg 1994 Dec
PMID:Comparison of the effects of aprotinin and tranexamic acid on blood loss and related variables after cardiopulmonary bypass. 752 12

Cyclic GMP accumulation in endothelial cells-smooth muscle cells (EC-SMC) coculture induced by both receptor-dependent (thrombin, bradykinin, BK) and receptor-independent (Ca(2+)-ionophore A23187) stimulation, was inhibited by preincubation with low-density lipoprotein (LDL) in time- and concentration-dependent manner. At least 5 min was necessary for the complete blockade with LDL (protein 1 mg/ml). LDL did not affect cyclic GMP-increase by sodium nitroprusside (SNP), a direct stimulator of SMC, but oxidized (ox)LDL (50-250 micrograms/ml) markedly reduced it. An increase of cyclic GMP accumulation in SMC by eluate from stimulated EC columns was completely blocked by 10-min pre-incubation of the column with LDL with or without superoxide dismutase (SOD). In contrast, preincubation of the SMC dish with LDL did not affect cyclic GMP accumulation by the eluate from the stimulated EC column, but preincubation with oxLDL (protein 50-100 micrograms/ml) greatly reduced it. Exposure time of released EDRF to LDL in both coculture and column experiments was < 40-45 s. These results suggest that a brief exposure of EC to pathophysiologic concentration of LDL exclusively affects EC functions, attenuating endothelium-derived relaxing factor (EDRF) release through intracellular mechanisms, and consumption of released EDRF by LDL does not appear to be involved in this LDL inhibitory effect. Possible inhibitory mechanisms of LDL are discussed.
J Cardiovasc Pharmacol 1994 Oct
PMID:Inhibition of EDRF release by native low-density lipoprotein from cultured porcine endothelial cells through intracellular mechanisms. 752 37

Thrombogenesis is considered the principal cause of early failure of arterial grafts. Although antithrombotic drugs are recommended, their efficiency under low blood flow conditions is still being debated. In this study, we evaluated the ability of three drugs to modify the thrombotic properties of blood and, consequently, to influence platelet and fibrin deposition on the luminal surface of polyester arterial prostheses. In dogs receiving saline (control, n = 10), heparin (100 U/kg, n = 5), aspirin (325 mg, n = 5), or prostacyclin (15 ng/kg/min, n = 5), a 30-cm, woven, loop-shaped, DeBakey arterial prosthesis was implanted as a substitute for the infrarenal aorta and exposed to reduced blood flow (50 ml/min) for 4 h. The parameters of the blood measured included activated clotting time (ACT) and platelet aggregation with collagen, determined before and after each treatment. Blood deposits were quantified using 111In labeled platelets and 125I-labeled fibrinogen. The ACT was significantly prolonged only after heparin treatment, and platelet aggregation, which was decreased by 35% (p < 0.05) after heparin treatment, was almost abolished after aspirin and prostacyclin treatments. As compared with the control group, both platelet and fibrin uptake on the luminal surface of the prostheses were reduced significantly by heparin by 87 and 37%, respectively. Despite their inhibition of platelet aggregation in vitro, aspirin and prostacyclin induced no significant change in platelet and fibrin deposition on the luminal surface of the woven polyester arterial prostheses under low blood flow conditions. Under such conditions, however, thrombin generation with subsequent platelet-fibrin deposition was prevented by use of heparin anticoagulant therapy.
J Cardiovasc Pharmacol 1995 Jul
PMID:Acute thrombogenicity of arterial prostheses exposed to reduced blood flow in dogs: effects of heparin, aspirin, and prostacyclin. 756 48


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