Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prostacyclin (PGI2) synthase is one of the key enzymes for vasodepressor PGI2 biosynthesis in the vascular wall. In this study, we attempted to define the alterations in PGI2 synthase and its role in the PGI2 generation in the vascular wall of deoxycorticosterone acetate (DOCA)-salt rats. The PGI2-generating capacity was enhanced significantly when DOCA-salt rats established hypertension, whereas the generation of other arachidonate metabolites, eg, PGE2, PGF2 alpha, and thromboxane, was unaltered. Moreover, the increase in PGI2 generation was associated with an increase in PGI2 synthase activity in the vascular wall. Indeed, the averaged PGI2 generating capacity was closely correlated to the averaged PGI2 synthase activity in DOCA-salt hypertensive rats and three lines of control rats. Incontrast, phospholipase C and phospholipase A2, both of which liberate arachidonate for PGI2 synthesis, were rather lowered in DOCA-salt hypertensive rats. These data clearly indicate that vascular PGI2 generation is increased in the development of DOCA-salt hypertension and that PGI2 synthase is mainly responsible for this enhancement. The increased PGI2 synthase may be relevant to the blood pressure elevation and is expected to have beneficial effects on the vascular protection in hypertension.
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PMID:Possible role of prostacyclin synthase in altered prostacyclin generation in DOCA-salt hypertensive rats. 193 Aug 48

Indapamide, a nonthiazide diuretic, exhibits direct vasodilator action as well as natriuretic and diuretic effects. Although calcium antagonist-like activity has been addressed so far, the mechanisms for vasodilator effect are still uncertain. To understand the wide range of indapamide actions, we examined the effects of indapamide on the vascular eicosanoid generation and investigated its mechanisms by using rat vascular smooth muscle cells in culture. Indapamide uniquely increased the prostacyclin generation in the vascular smooth muscle cells in a dose-dependent manner, whereas it did not affect the vasoconstrictor thromboxane A2. Thiazide diuretics lowered the prostacyclin generation, while nonthiazide derivatives did not affect the biosynthesis. Enzymatic analysis revealed that indapamide affected neither [14C]arachidonate liberation nor prostacyclin synthase of the smooth muscle cells. Indapamide eliminated a stable free radical in a cell-free system, lowered the formation of malondialdehyde from lipid peroxides in rat brain homogenate, and reduced lipid peroxidation by the free radical generating system of xanthine-xanthine oxidase. Indeed, the scavenging action of indapamide significantly attenuated the inhibitory activity of 15-hydroperoxy-arachidonate to prostacyclin synthase activity. These results indicate that indapamide diuretic increases prostacyclin generation in the vascular smooth muscle cells possibly through antioxidant effects and that the enhanced prostacyclin generation is partly responsible for its direct vasodilator action.
Hypertension 1990 Feb
PMID:Radical scavengers of indapamide in prostacyclin synthesis in rat smooth muscle cell. 210 10

Characterization of the PGI2 producing enzyme system (P.E.S.) in pregnancy induced hypertension (PIH) was carried out by comparing its conversion from arachidonic acid (A.A.) or PGH2 to PGI2 using enzyme preparations from endothelial cells of the umbilical vein in normal pregnancy (N) and mild (M) and severe (S) types of PIH. 1) The conversion rate from A.A. to PGI2 in N was significantly (p less than 0.05) higher than in M and S. 2) The conversion rate from PGH2 to PGI2 in N was higher than in M and that in M was higher than in S. 3) The apparent Vmax values (nM/mg protein) (mean +/- S.E.M.) for P.E.S. in N (0.88 +/- 0.21) were significantly (p less than 0.05) lower than in M (2.76 +/- 0.71) and S (1.63 +/- 0.18). The apparent Km values (microM) (mean +/- S.E.M.) for P.E.S. in N (0.76 +/- 0.25) were significantly (p less than 0.05) higher than in M (0.29 +/- 0.07) and significantly (p less than 0.05) lower than in S (3.26 +/- 0.78). 4) The apparent Vmax values for PGI2 synthetase (P.S.) in N (0.44 +/- 0.09) and M (0.61 +/- 0.10) were significantly (p less than 0.05) higher than in S (0.11 +/- 0.06). The apparent Km values for P.S. in N, M and S were 0.12 +/- 0.07, 0.13 +/- 0.06 and 0.16 +/- 0.04, respectively. The present study showed that the symptoms in M may be kept from becoming aggravated by the production of large amounts of PGI2, due mainly to activation of cyclooxygenase, whereas progressive disorder of the regulation of blood pressure in S may be caused by low production of PGI2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Significance of the PGI2 producing enzyme system in the pathogenesis of pregnancy-induced hypertension]. 212 Mar 73

A rat aortic explant culture system was developed for the investigation of the effects of hydrocortisone (HC) and the glucocorticoid antagonist, RU486, on prostacyclin (PGI2 synthesis. HC, but not aldosterone, progesterone, 17 beta-estradiol, or testosterone, inhibited spontaneous, epinephrine-stimulated and U46619 (an analog of thromboxane A2)-stimulated PGI2 synthesis by cultured aortic explants in a concentration- and time-dependent manner. Adequate inhibition of aortic explant PGI2 synthesis by physiological concentrations of HC was achieved after an 18-h culture. An 18-h time course was employed in subsequent experiments. In contrast, HC had no effect on arachidonic acid-stimulated PGI2 synthesis. Protein synthesis inhibitors, actinomycin D and cycloheximide, had no effect on the inhibitory action of HC on epinephrine- and U46619-induced release of PGI2. They exerted a direct inhibitory effect on aortic PGI2 synthesis. Arachidonic acid stimulated PGI2 release by the explants and was unaffected either by HC or by treatment with cycloheximide or actinomycin D. RU486 blocked the inhibitory action of HC on aortic PGI2 synthesis in a dose-dependent manner. Thus, the inhibitory effect of HC on vascular PGI2 synthesis is probably mediated through an inhibition of phospholipase A2 and not cyclooxygenase or other PGI2 synthase systems; furthermore, this inhibitory effect is not dependent upon de novo protein synthesis. RU486 antagonizes the inhibitory effect of HC. The inhibition of vascular PGI2 by hydrocortisone has implications in the pathogenesis of steroid-related hypertension and atherosclerosis and the antiinflammatory effect of steroids.
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PMID:Inhibition by hydrocortisone of prostacyclin synthesis by rat aorta and its reversal with RU486. 308 61

To reveal the role of enzymes involved in PGI2 synthesis for vascular PGI2 generation in experimental hypertensive models, we defined PGI2 synthase and phospholipases activities in the aortic wall of two different experimental hypertensive rats, e.g. spontaneously hypertensive rats (SHR) and desoxycorticosterone acetate (DOCA)-salt hypertensive rats. In the stage of established hypertension both of the hypertensive models had a significantly large capacity of the vascular wall to produce PGI2, as compared to respective control rats. PGI2 synthase activities in the vascular wall were significantly increased by 27% for SHR and by 80% for DOCA-salt hypertensive rats. Moreover, the enzymatic activities were closely related to the blood pressure values for both of the models. On the other hand, phospholipase C or phospholipase A2 activities were increased or unchanged in SHR, respectively, whereas both of the phospholipases were significantly decreased in DOCA-salt hypertensive rats. Thus, it is indicated that PGI2 synthase is partly responsible for the increased PGI2 generation in the vascular wall of SHR and DOCA-salt hypertensive rats, and that vascular phospholipase C is playing a more important role in providing arachidonate for PGI2 synthesis in SHR.
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PMID:Prostacyclin synthase and phospholipases in the vascular wall of experimental hypertensive rats. 312 12

To define the roles of vascular prostacyclin (PGI2) synthase for PGI2 generation in deoxycorticosterone acetate (DOCA)-salt hypertension, we investigated PGI2 synthase, phospholipase A2 and phospholipase C activities in the aortic wall of DOCA-salt prehypertensive and established hypertensive rats. Vascular PGI2 generation in the DOCA-salt hypertensive rats was increased by 91%, and was associated with an 88% increase in PGI2 synthase activity and lowered phospholipase C and A2 activity. In the prehypertensive stage, DOCA-salt rats showed reduced vascular PGI2 generation. Prostacyclin synthase activity was equal to that of controls. These data clearly suggest that DOCA-salt hypertensive rats increase their vascular PGI2 generation when they develop hypertension, and that this may be due to the activation of vascular PGI2 synthase.
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PMID:Alterations to the vascular vasodepressor prostaglandin system in DOCA-salt hypertensive rats and their enzymatic analysis. 324 Dec 24

Uterine prostacyclin synthase (PGI synthase) and prostaglandin endoperoxide synthase (PGH synthase) concentrations, measured by specific immunoradiometric assays, did not differ between patients with severe pregnancy-induced hypertension (syn. pre-eclampsia; n = 5) and normotensive gravidae (n = 6) with comparable gestational ages (34 - 38 weeks). Myometrial microsomes from pre-eclamptic women contained ten times more PGI synthase than PGH synthase and the ratio of PGI synthase to PGH synthase (mean +/- SD; 10.1 +/- 3.9) was not different from that in normotensive pregnancies. None of the pre-eclamptic patients had myometrial enzyme levels that were more than one standard deviation below the mean established previously for pregnancies ranging from 32 to 42 weeks of gestation. These findings indicate that the commonly observed association between deficient PGI2 production and pregnancy-induced hypertension cannot be explained in terms of a generalized lack of immunoassayable prostacyclin or prostaglandin endoperoxide synthases.
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PMID:Control of prostacyclin synthesis in pregnancy-induced hypertension. 392 69

In addition to the hemodynamic components, the roles of various humoral factors have been emphasized in the progression of vascular and renal injury in hypertension. Radical scavenging properties have attracted much attention in this field. This article discusses the implication of antioxidant properties of the antihypertensive diuretic indapamide on renal injury in Dahl salt-sensitive (Dahl S) rats. Hydroxyl radicals, oxygen radicals toxic to cellular membranes, are eradicated by indapamide in different assay systems, e.g., reduction of alpha-alpha-diphenyl-beta-picrylhydrazyl, rat brain homogenate, or xanthine-xanthine oxidase systems. Such antioxidant effects of indapamide are primarily due to inhibition of lipid peroxidation induced by hydroxyl radicals, and this mechanism may stimulate prostacyclin generation through activation of prostacyclin synthase. In fact, the antioxidant properties of indapamide are well expressed in vivo as well; indapamide treatment reduced oxygen radicals in the kidney of Dahl S rats with hypertension. This was accompanied by a functional improvement of the kidney; decreases in urinary protein and n-acetylglucosaminidase excretion and an increase in glomerular filtration rate were observed. In addition, indapamide morphologically ameliorated the renal injury, and decreased glomerular sclerosis score, arterial injury, and renal tubular injury. Trichloromethiazide reduces blood pressure similar to that produced by indapamide. However, trichloromethiazide did not lead to reduction of oxygen radicals in the kidney, and did not improve the functional disturbance or morphological injury seen in Dahl S rats. These results indicate that indapamide has antioxidant properties, and in addition to blood pressure reduction, such radical scavenging effects may contribute to its beneficial effects on renal function in vivo.
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PMID:Oxygen radical scavengers and renal protection by indapamide diuretic in salt-induced hypertension of Dahl strain rats. 750 60

Preeclampsia is a disease of late pregnancy characterized by hypertension, edema, and proteinuria, in which vasoconstriction, platelet aggregation, and reduced uteroplacental blood flow contribute to preterm delivery, perinatal morbidity, and mortality. Increased thromboxane-A2 (TXA2) and/or decreased prostacyclin (PGI2) have been implicated as causative factors of this disease. The present studies investigated the expression of TXA2 synthase gene along with those of TXA2 receptors, PGI2 synthase, cyclooxygenase-1 (COX-1), and COX-2 in placental and decidual tissue from preeclamptic and normal pregnancies. In situ hybridization and immunocytochemistry showed that primarily trophoblast layer and decidual cells express TXA2 synthase, COX-1, and COX-2 enzymes. Immunocytochemistry for PGI2 synthase and in situ hybridization for TXA2 receptors showed similar results. Trophoblast layer and decidua from preeclamptic pregnancies contained a greater abundance of mRNA and protein of TXA2 synthase than the matched normal pregnancies. In summary, our findings suggest that an increased local expression of TXA2 synthase could be responsible for local and/or peripheral vascular changes in preeclampsia.
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PMID:Eicosanoid biosynthetic enzymes in placental and decidual tissues from preeclamptic pregnancies: increased expression of thromboxane-A2 synthase gene. 817 82

Much interest in cicletanine, a novel antihypertensive drug, has grown because it uniquely stimulates prostacyclin (PGI2) production and may, thereby, provide further cardiovascular protection. We postulated that cicletanine may be an antioxidant, and assessed its ability to protect the kidney in Dahl salt-sensitive (Dahl S) rats on a high salt diet. Cicletanine eradicated in vitro a stable radical, DPPH, and decreased the lipid peroxidation both in rat brain homogenate and in a xanthine-xanthine oxidase (X-XOD) superoxide generating system. Furthermore, cicletanine attenuated the inhibition of PGI2 synthase activity by 15HPETE. However, cicletanine did not exhibit superoxide dismutase-like activity in X-XOD system, suggesting that it behaves primarily as a hydroxy radical scavenger. A 6 week cicletanine treatment reduced blood pressure in Dahl S rats fed a high salt diet, and ameliorated functional and morphological injury to the kidney. This attenuation of glomerular sclerosis correlated with the attenuation of lipid peroxidation in the kidney homogenate. These data indicate that cicletanine is an antioxidant that protects the kidney from salt-induced hypertension in Dahl salt-sensitive strain rats.
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PMID:Possible radical scavenging properties of cicletanine and renal protection in Dahl salt sensitive rats. 834 28


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