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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amounts of tissue factor (TF) expressed by brain microvascular endothelial cells (BMECs) from normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were compared after stimulating the cells with different doses of lipopolysaccharide (LPS), thrombin, phorbol myristic acid (PMA), Ca(2+)-ionophore (A23187), or tumor necrosis factor (TNF) and interleukin-1 (IL-1). Treatment of cultured BMECs from WKY and SHR with all of these factors dose-dependently increased their total amount of TF; no substantive differences in the levels of enhanced TF expression were observed between WKY and SHR BMECs. We conclude that stimulated endothelium from rats with hypertension, a major stroke risk factor, is not hyperresponsive with respect to TF expression when compared to normotensive controls.
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PMID:Comparison of stimulated tissue factor expression by brain microvascular endothelial cells from normotensive (WKY) and hypertensive (SHR) rats. 147 6

As a source of several vasoactive factors, the endothelium takes part in the regulation of vascular tone. The most important endothelium-derived vasoactive substances are nitric oxide, prostacyclin, endothelin-1 and contracting factors requiring the activity of cyclooxygenase. The endothelium is an obvious target organ of cardiovascular risk factors. Accordingly, functional alterations do occur with aging, hypertension and hypercholesterolaemia. All three conditions are associated with a decreased basal and simulated release of endothelium-derived nitric oxide. On the other hand, the release of endothelin-1 appears to increase with age, while the sensitivity to the peptide markedly decreases under the same conditions. In the spontaneously hypertensive rat, acetylcholine and stretch evoke the release of a cyclooxygenase-dependent endothelium-derived contracting factor, most likely prostaglandin H2. The circulating levels of endothelin-1 on the other hand are not increased in experimental and human hypertension. In the porcine coronary circulation, oxidized low-density lipoproteins selectively reduced endothelium-dependent relaxations to aggregating platelets, serotonin and thrombin which are mediated by nitric oxide. The alterations of endothelial function occurring with aging, hypertension and hypercholesterolaemia may have important clinical implications for the pathogenesis of cardiovascular disease.
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PMID:Age, hypertension and hypercholesterolaemia alter endothelium-dependent vascular regulation. 150 46

Increased plasma fibronectin levels are a highly sensitive and specific predictor of gestational hypertension. Of a total of 105 apparently healthy normotensive primigravid women seen at the outpatient clinic, 10 with increased plasma levels of fibronectin (mean +/- 2 SD), were compared with 14 controls. Parameters of early vascular damage (laminin, preprocollagen III), platelet activation (beta-thromboglobulin, platelet factor 4), and coagulation (thrombin-antithrombin III complexes, fibrinopeptide A) were measured at regular (weekly or monthly) intervals. Abnormal values of laminin (p less than 0.005) and fibronectin (p less than 0.0001) were found up to 4 weeks before the onset of clinical disease. Levels of beta-thromboglobulin (p less than 0.0001) were also elevated at least 4 weeks before the appearance of clinical symptoms. Our results show that increased levels of laminin, fibronectin, and platelet activation, as indicated by beta-thromboglobulin levels, are preclinical features of gestational hypertension and indicate that vascular damage has occurred. Fibrin formation would appear to occur later.
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PMID:Platelet activation and vascular damage in gestational hypertension. 153 75

Endothelin is a newly discovered potent vasoconstrictive polypeptide released by endothelial cells in response to various stimuli, including vasoactive peptides such as angiotensin II, adrenaline and vasopressin, and thrombocyte products like transforming beta growth factor and thrombin. Endothelin is believed to exert its main effects locally, in a paracrine or autocrine way. In vascular tissue, endothelin induces longlasting contraction of smooth muscle cells, leading to decreased blood flow, especially in the coronary and renal circulation, together with an increase in systemic blood pressure. It acts also mitogenically in vascular smooth muscle cells. Endothelin stimulates release of aldosterone and catecholamines in non-vascular tissue, and inhibits release of renin. A physiological function of endothelin may be to modulate vascular tone, and increased levels of circulating endothelin are seen after the "cold pressor test". Moreover, plasma endothelin concentration is elevated during acute myocardial infarction, in acute renal failure, in patients with hypertension, and during cardiogenic chock. What role endothelin plays in the development of these conditions, and in other disorders such as vascular spasm and atherosclerosis is uncertain.
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PMID:[The endothelial cell as an endocrine organ--endothelin]. 155 33

By using aortic adventitial fibroblasts in culture as a model, we first demonstrated that cells derived from spontaneously hypertensive rats (SHR), when compared with Wistar-Kyoto (WKY)-derived cells, possessed an increased capacity to proliferate and to synthesize DNA in response to vasoactive agents. At this early stage of culture, SHR fibroblasts exhibited a higher specific growth rate. Then, to gain insight into the mechanisms which could be responsible for the difference observed, signalling pathways involved in the transduction of the mitogenic signal were analysed in cells cultured for 3 days. Results indicated that, in SHR-derived fibroblasts, an increased phospholipase C activity could account for the higher mitogenic response to thrombin or vasopressin. However, this enzymatic activity, which did not differ when fibroblasts from the two rat strains were stimulated by serum, could not be responsible for the enhanced proliferation rate of SHR-derived cells. Moreover, neither protein kinase C nor pertussis toxin-sensitive G proteins appeared to contribute to the hyperresponsiveness exhibited by SHR fibroblasts. Our results indicate that the mechanism(s) responsible for such a difference vary according to the stimulus; they also suggest that adventitial fibroblasts may participate in the modified reactivity of vascular wall associated with hypertension.
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PMID:Increased proliferation of adventitial fibroblasts from spontaneously hypertensive rat aorta. 166 71

Human mesangial cells in culture proliferate in response to platelet-derived growth factor (PDGF) and thrombin. Both of these agents also induce changes in cytosolic calcium that are dependent on both mobilization of intracellular calcium and influx of extracellular calcium. We hypothesized that calcium channel blockers, by preventing influx of extracellular calcium, may inhibit proliferation induced by these mitogens. We found that three different calcium channel blockers, diltiazem, nifedipine, and verapamil, were able to significantly inhibit [3H]thymidine incorporation into human mesangial cells induced by either PDGF or thrombin. The inhibitory effect of these agents was significant at 10(-5) M. The calcium channel blockers also attenuated the increases in cell number and percentage of labeled nuclei induced by these mitogens. In contrast, dantrolene, an inhibitor of intracellular calcium mobilization, had no significant effect on [3H]thymidine incorporation by PDGF or thrombin. Finally, the calcium channel agonist, Bay K 8644 was found to stimulate [3H]thymidine incorporation into mesangial cells. Although the mechanisms for these effects of calcium channel blockers are not proven, these studies suggest that influx of extracellular calcium is an important signal in mitogen-induced mesangial proliferation and that these agents can be beneficial in preventing or attenuating renal diseases characterized by proliferation of these cells.
Hypertension 1990 Feb
PMID:Inhibition of human mesangial cell proliferation by calcium channel blockers. 168 25

Determinations of thrombin/antithrombin III complex (TAT) in human plasma with the new enzyme immunoassay (Enzygnost-TAT) were performed. The study group consisted of 36 patients aged 36-79 years suffering from peripheral obliterative arterial disease (POAD) comparing to control group. In patients the elevation of TAT level was detected. The analysis of increased TAT level in the relation to clinical atherosclerotic complications, the kind of treatment, the stage of POAD, the age of patients and the period after operation was done. The highest TAT complex seemed to be correlated with the advance of atherosclerotic process, with additional diseases such as arterial hypertension, diabetes mellitus and performed operation. The "Enzygnost-TAT" assay can be useful for the detection of prethrombotic states without clinical symptoms of hypercoagulability and can be applied for clinical diagnosis.
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PMID:Thrombin/antithrombin III complex in patients with peripheral occlusive arterial disease. 170 10

Endothelial cells can produce contracting factors; endothelin, a 21-amino acid peptide that can control local vascular tone, is the most potent of these factors. Of the three isoforms of endothelin, endothelial cells appear to release primarily endothelin-1. The peptide is formed from its precursor big endothelin via the activity of the endothelin converting enzyme. The basal production of the peptide is stimulated by epinephrine, angiotensin II, arginine vasopressin, transforming growth factor beta, thrombin, interleukin-1, and the calcium ionophore A23187. In vascular smooth muscle cells, endothelin binds to a specific receptor that activates phospholipase C and leads to the formation of inositol trisphosphate, diacylglycerol, and increased intracellular calcium levels. In certain blood vessels, the endothelin receptor is linked to a voltage-operated calcium channel via a Gi protein. This may explain why calcium antagonists inhibit endothelin-induced contractions only in certain blood vessels. In the human forearm circulation, calcium antagonists of different classes prevent endothelin-induced contractions. In hypertension, the circulating endothelin levels appear to be normal, whereas the vascular sensitivity to the peptide is reduced in most vascular tissues, but normal and enhanced responses have also been reported. In atherosclerosis and other forms of vascular disease, circulating endothelin levels are augmented, a phenomenon that may be related to an increased formation of the peptide induced by modified forms of low-density lipoproteins.
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PMID:Endothelin. 172 99

We previously reported an enhanced peak response of intracellular free Ca2+ to thrombin in platelets of spontaneously hypertensive rats in comparison with normotensive Wistar-Kyoto rats. In the present study, we compared the platelet intracellular Ca2+ response to the receptor-linked agonist thrombin with the response to the Ca2+ ionophore ionomycin. Basal intracellular Ca2+ was higher in hypertensive platelets as was leakage of fura-2. We confirmed the previous finding that the thrombin-induced intracellular Ca2+ peak is greater in platelets of hypertensive rats and noted that the rate of recovery from peak intracellular Ca2+ is significantly greater in this model. In contrast, the peak platelet intracellular Ca2+ response to ionomycin (50 nM and 5 microM) was not different between the two strains, and the rate of recovery from the peak response was only slightly depressed in hypertensive rats after the low dose of ionomycin. Internal Ca2+ discharge capacity, assessed by the intracellular Ca2+ response to a maximal dose of ionomycin in Ca(2+)-free medium, was not different between platelets of the two strains. Thus, activated platelet intracellular Ca2+ is not altered in the hypertensive rat when the nonphysiological ionophore ionomycin is used as agonist. However, a heightened intracellular Ca2+ response is observed when the receptor-mediated agonist thrombin is used. These results are consistent with the hypothesis that differences in receptor-linked second messenger pathways underlie the altered intracellular Ca2+ response in platelets of genetically hypertensive rats and may contribute to differences both in the mobilization of Ca2+ and in its fall.
Hypertension 1991 Dec
PMID:Rise and fall of agonist-evoked platelet Ca2+ in hypertensive rats. 174 57

This report describes a French Canadian family whose members exhibit a high incidence of allo- and autoantibodies to antigens present on both platelets and endothelial cells. This is correlated with various HLA specificities known to be associated with autoimmunity, such as A1, B8, DR3, and, in some cases, with clinical disorders, including nephritis, hypertension, and thrombocytopenia. Immunoblot analysis using platelet and endothelial cell lysates showed serum antibodies to a 75 kDa endothelial cell surface polypeptide and to polypeptides with apparent mass of 115 kDa and 26 kDa found on both platelets and endothelial cells. This 115 kDa internal platelet protein was also found in a variety of other cell types, such as mononuclear cells, and increased following cell activation. Monoclonal antibody immunobilization assays were used to characterize the 26 kDa polypeptide; in three of the four patients tested, an antibody to leukocyte differentiation antigen CD9 was identified. The asymptomatic child of the propositus also exhibited an autoantibody against an 80 kDa platelet protein which was sensitive to thrombin digestion, suggesting that this polypeptide may be platelet glycoprotein V. In addition, P1A1 alloantibody was identified in one sister who had given birth to a severely thrombocytopenic boy and who herself had a severe vascular rejection to a cadaver kidney 2 years prior to this study. The propositus also developed hypertensive renal disease following a pregnancy and became dialysis dependent. Thus, members of this family have developed a variety of antibodies, particularly to platelet and endothelial cell antigens. Some subjects have remained asymptomatic in spite of having autoantibodies. However, others have been seriously ill, and their immune response to these antigens is believed to have played a role in the pathogenesis of their neonatal alloimmune thrombocytopenic purpura, hypertensive renal disease, renal graft rejection, and thrombocytopenia.
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PMID:Characterization of novel platelet and endothelial cell target antigens in a family with genetic susceptibility to autoimmunity. 174 38


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