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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A within-patient randomized double-blind crossover study was performed on mechanisms of action of bendrofluazide in mild essential hypertension. Significant reductions in lying, standing and post-exercise blood pressure were seen after both 3 days and 10 weeks treatment with bendrofluazide (10 mg daily). 2. Plasma levels of 6-oxo-prostaglandin F1 alpha, the chemical hydrolysis product of prostacyclin, were significantly increased by both 3 days and 10 weeks therapy with bendrofluazide. This raises the possibility that thiazides may reduce peripheral resistance by increasing prostacyclin biosynthesis.
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PMID:Circulating prostacyclin concentrations may be increased by bendrofluazide in patients with essential hypertension. 700 20

The time courses of mean blood pressure (MBP), plasma renin activity (PRA), plasma aldosterone (PA), serum prostaglandin E (PGE), serum angiotensin I converting enzyme (ACE), and blood levels of angiotensin I converting enzyme inhibitor (SQ 14,225) (captopril) were studied in 6 patients with essential hypertension (5 men and 1 woman, aged 44 +/- 5.6 (mean +/- S.E.) years) before and 30, 60, 120 and 180 min after administration of 25 mg captopril. MBP and ACE began to fall within 30 min and reached a significant minimum between 60 and 180 min after captopril administration. PRA was significantly increased 60 min after captopril administration and continued for 180 min. On the other hand, PA had begun to fall significantly 180 min after captopril administration. The blood levels of captopril were significantly increased 30 min after captopril administration, with a peak at 120 min. The levels at 180 min were half the peak. The levels of PGE were not significantly changed within 180 min after captopril administration. These results suggest a discrepancy between the changes in MBP and the blood levels of captopril. The blood pressure lowering effect may be due to inhibition of angiotensin II (Ang. II) during the short-acting effect, and due to decrease of PA, metabolites of captopril, increase of kinin in the blood, inhibition of the slow pressor effect of Ang. II, increases of other depressor hormones such as prostacyclin and other depressor mechanisms during the long-acting effect.
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PMID:Relationship between blood pressure and blood levels of angiotensin I converting enzyme inhibitor (SQ 14,225). 702 28

Altered prostacyclin metabolism may underlie essential hypertension. In this study, responses of plasma 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha: a stable metabolite of prostacyclin) to infused norepinephrine (NE) were compared in 14 normotensive subjects (NT) and 20 untreated patients with essential hypertension (EH). In addition, changes in systemic hemodynamics following NE-infusion were compared with changes in plasma 6-keto-PGF1 alpha. The subjects were all hospitalized and placed on a diet containing 6-8 g of salt per day. Blood pressure was recorded directly through the brachial artery, cardiac output (CO) was determined with the dye-dilution technique using cuvette and total peripheral vascular resistance (TPR) was calculated before and 60 min after NE-infusion. Arterial plasma 6-keto-PGF1 alpha was also determined before and after NE-infusion. The rate of NE-infusion was adjusted to elevate mean arterial pressure (MAP) by 10-15%. Plasma 6-keto-PGF1 alpha was radioimmunoassayed. Elevation of MAP was 13.0 +/- 1.2 (SE) in NTs and 11.7 +/- 1.4% in EHs. After NE-infusion, CO and TPR both significantly increased in NTs, while only CO increased significantly in EHs. Changes in CO and TPR were both significantly different between the two groups (p less than 0.01). Initial plasma 6-keto-PGF1 alpha was reduced in EHs as compared with NTs (174 +/- 15 vs 295 +/- 41 pg/ml, p less than 0.02). However, during NE-infusion, the increase in plasma 6-keto-PGF1 alpha was greater in EHs than in NTs (p less than 0.01). There was a significant negative correlation between changes in TPR and plasma PG (r = -0.36, p less than 0.05). The results indicate that responses of systemic hemodynamics and plasma 6-keto-PGF1 alpha to infused NE are different in the NT and EH groups, and that the absence of changes in TPR in EHs may be related to a marked increase in circulating prostacyclin. These findings, together with the reduced initial levels of plasma 6-keto-PGF1 alpha in EHs, probably represent altered prostacyclin metabolism in essential hypertension.
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PMID:Effects of norepinephrine infusion on systemic hemodynamics and plasma 6-keto-prostaglandin F1 alpha in normotensive subjects and patients with essential hypertension. 704 17

Mortality and morbidity from coronary heart disease (CHD), diabetes mellitus (DM) and essential hypertension (HTN) are higher in people of South Asian descent than in other groups. There is evidence to believe that essential fatty acids (EFAs) and their metabolites may have a role in the pathobiology of CHD, DM and HTN. Fatty acid analysis of the plasma phospholipid fraction revealed that in CHD the levels of gamma-linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are low, in patients with HTN linoleic acid (LA) and AA are low, and in patients with non-insulin dependent diabetes mellitus (NIDDM) and diabetic nephropathy the levels of dihomo-gamma-linolenic acid (DGLA), AA, alpha-linolenic acid (ALA) and DHA are low, all compared to normal controls. These results are interesting since DGLA, AA and EPA form precursors to prostaglandin E1, (PGE1), prostacyclin (PGI2), and PGI3, which are potent platelet anti-aggregators and vasodilators and can prevent thrombosis and atherosclerosis. Further, the levels of lipid peroxides were found to be high in patients with CHD, HTN, NIDDM and diabetic nephropathy. These results suggest that increased formation of lipid peroxides and an alteration in the metabolism of EFAs are closely associated with CHD, HTN and NIDDM in Indians.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Essential fatty acid metabolism in patients with essential hypertension, diabetes mellitus and coronary heart disease. 764 60

Angiotensin converting enzyme inhibitors have been proposed to have a prostaglandin-dependent component to their hypotensive action. The aim of this study was to assess whether the structurally dissimilar angiotensin converting enzyme inhibitors captopril and enalapril stimulate the synthesis of prostacyclin, whether their hypotensive action is blunted by indomethacin, and whether these biochemical or physiologic parameters differ for the two drugs, in white subjects with essential hypertension. Twelve patients were enrolled and 11 finished the study. The study consisted of a double blind, randomized, double-crossover design. All patients received either placebo or 50 mg indomethacin twice a day for 3 weeks; after 1 week of placebo or indomethacin either 50 mg captopril or 10 mg enalapril twice a day was added and continued for 2 weeks. Each patient received every possible combination. Neither captopril nor enalapril stimulated prostacyclin production as determined by measurement of the urinary excretion rate of its main enzymatic metabolite, 2,3-dinor-6-keto-prostaglandin-F1 alpha. Although indomethacin reduced the urinary excretion of the enzymatic metabolite of prostacyclin by more than 50%, it did not influence the hypotensive effect of captopril or enalapril. We conclude that neither captopril nor enalapril have a significant prostacyclin-dependent component to their hypotensive action.
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PMID:The hypotensive action of captopril and enalapril is not prostacyclin dependent. 822 95

Possible involvement of reactive oxygen species and nitric oxide in the pathogenesis of human essential hypertension was investigated. It was observed that both superoxide anion and hydrogen peroxide production by polymorphonuclear leukocytes and the plasma levels of lipid peroxides are higher in uncontrolled essential hypertension compared with normal controls. Nitric oxide levels measured as its stable metabolite nitrite, as an index of nitric oxide synthesis, revealed its levels to be low in hypertensive patients. Superoxide anion, hydrogen peroxide, lipid peroxides and nitric oxide levels reverted to normal values after the control of hypertension by drugs. The concentrations of anti-oxidants such as vitamin E and superoxide dismutase were found to be decreased in patients with uncontrolled hypertension. Several anti-hypertensive drugs inhibited lipid peroxidation in vitro. Angiotensin-II, a potent vasoconstrictor, stimulated free radical generation in normal leukocytes which could be blocked by calmodulin antagonists. These results suggest that an increase in free radical generation and a simultaneous decrease in the production of nitric oxide and anti-oxidants such as SOD and vitamin E occurs in essential hypertension. This increase in free radical generation can inactivate prostacyclin and nitric oxide and decrease their half life which can lead to an increase in peripheral vascular resistance and hypertension.
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PMID:Are free radicals involved in the pathobiology of human essential hypertension? 822 35

Some of the antihypertensive effects of angiotensin-converting enzyme (ACE) inhibitors occur through nonangiotensin II-mediated mechanisms. One of these is through decreased kinin degradation, leading to enhanced production of vasodilator arachidonic acid metabolites. It was reasoned that if ACE inhibition also leads to an increase in the production of the potent vasoconstrictor thromboxane A2, then maneuvers that selectively inhibit thromboxane production without reducing prostaglandins (PG) E2 + PGI2 might enhance the antihypertensive effect of ACE inhibition. This double-blinded, randomized, crossover study was therefore undertaken to determine: (1) if captopril increases platelet and/or renal thromboxane production; and (2) if low-dose aspirin enhances the antihypertensive effect of captopril. Patients with mild essential hypertension and no other significant medical problems were studied. In a double-blinded, random order, patients took captopril alone (25 mg every 12 h) for 2 wk and captopril plus aspirin (75 mg/day) for another 2 wk. Active treatment periods were preceded by 2 wk of single-blind placebo. Fifteen patients with a mean age of 53 yr and an average mean arterial pressure (MAP) of 114 +/- 8 (+/- SD) mm Hg were studied. Serum thromboxane B2 was higher (P < 0.05) during treatment with captopril/placebo (600 +/- 46 (+/- SE) pg/mL) than during the two washout periods combined (420 +/- 57 and 553 +/- 78) and was lowest (P < 0.0005) during treatment with captopril/aspirin (302 +/- 36). Captopril treatment significantly increased the urinary excretion of PGE2 (P = 0.038). Captopril/placebo significantly lowered MAP (P < 0.05) to 105.0 +/- 3.7 mm Hg compared with the washout period. However, the addition of aspirin to captopril caused no additional lowering of MAP (105.2 +/- 2.8 mm Hg). It was concluded that treatment with captopril does increase platelet thromboxane production. However, lowering platelet thromboxane with low doses of aspirin may not enhance the antihypertensive effect of captopril.
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PMID:Effect of low-dose aspirin on thromboxane production and the antihypertensive effect of captopril. 830 40

Short-term effects of ridogrel, a combined thromboxane synthase inhibitor and receptor antagonist, were investigated in 16 patients with uncomplicated essential hypertension. After a 2-week placebo period without antihypertensive medication, patients were admitted to the hospital overnight on two occasions 3 weeks apart. On each occasion, they received two doses of either placebo or ridogrel (300 mg) 12 hours apart according to a double-blind crossover protocol. Renal and systemic thromboxane A2 and prostacyclin biosynthesis were investigated by measuring urinary excretion of thromboxane B2, 6-oxo-prostaglandin F1 alpha, and their respective 2,3-dinor metabolites using gas chromatography/mass spectrometry. Responses of platelets to a thromboxane A2 mimetic and to adenosine diphosphate were studied turbidometrically. Blood pressure was measured automatically at 20-minute intervals. Ridogrel reduced excretion of 2,3-dinor-thromboxane B2 and thromboxane B2 compared with placebo (21 +/- 6 versus 279 +/- 28 and 14 +/- 4 versus 39 +/- 9 ng/g creatinine, respectively; P < .0001 and P < .05). Excretion of 2,3-dinor-6-oxoprostaglandin F1 alpha and 6-oxoprostaglandin F1 alpha was increased by ridogrel compared with placebo (184 +/- 20 versus 146 +/- 11 and 86 +/- 9 versus 58 +/- 6 ng/g creatinine, respectively; P < .05). Ridogrel selectively antagonized platelet aggregation to the thromboxane mimetic (P < .0001). Blood pressure did not differ significantly between ridogrel and placebo treatment periods. Thus, in patients with essential hypertension, acute administration of ridogrel reduces renal and extrarenal thromboxane A2 biosynthesis, increases renal and extrarenal prostacyclin biosynthesis, inhibits thromboxane receptor-activated platelet aggregation, but has no effect on systemic arterial pressure.
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PMID:Thromboxane A2 receptor antagonism and synthase inhibition in essential hypertension. 834 Jan 55

Cicletanine is a new antihypertensive drug that stimulates renal and vascular synthesis of prostaglandin (PG) I2 in experimental animals. However, there is little evidence that cicletanine increases the level of PGI2 in systemic blood of human subjects. To investigate the short-term antihypertensive mechanism of cicletanine, we measured serially the systemic blood pressure, the levels of 6-keto-PGF1 alpha (a stable metabolite of PGI2) and PGE2, and renin activity in plasma after administration of the drug. Nine patients with essential hypertension on a diet without severe sodium restriction took 100 mg of the drug by mouth. Systemic blood pressure was measured hourly for 24 h before and after cicletanine administration. The two PGs of interest were extracted, purified by high pressure liquid chromatography, and measured by radioimmunoassay. Cicletanine decreased blood pressure 3 and 6 h after administration and increased the plasma level of 6-keto-PGF1 alpha. The increase in 6-keto-PGF1 alpha was small but significant (mean +/- SD, from 3.21 +/- 1.26 to 3.88 +/- 1.44 and later 4.15 +/- 1.08 pg/mL by 3 and 6 h after administration; P < .05 and .01, respectively). The level of PGE2 had increased at 3 h after administration but returned to baseline by 6 h. Plasma renin activity was increased only at 24 h after administration. Cicletanine increased systemic PGI2 levels short-term, producing an antihypertensive effect in patients with essential hypertension.
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PMID:Short-term increase in prostaglandin I2 synthesis caused by cicletanine in patients with essential hypertension. 854 Oct 11

Protacyclin biosynthesis was investigated in 133 untreated newly diagnosed patients with uncomplicated essential hypertension. Urinary excretion of 6-oxo-prostaglandin F1 alpha and of 2,3-dinor-6-oxo-prostaglandin F1 alpha, stable breakdown products of prostacyclin, was measured following a 1 month run-in period. To determine whether lowering blood pressure (BP) influenced prostacyclin biosynthesis, 106 consenting patients with diastolic pressure 90-120 mm Hg were allocated randomly to treatment with bendrofluazide, metoprolol, quinapril or amlodipine in an open parallel group design. Dose was increased to reduce diastolic arterial pressure to <90 mm Hg. Terazosin was added if this target BP was not achieved, and its dose increased if necessary. Urinary excretion rates of prostaglandins were measured after 1 year in patients in whom the target diastolic pressure was achieved. Mean arterial pressure varied from 106-168 mm Hg in untreated patients and excretion of both prostacyclin-derived products varied from <5 to >350 ng/g creatinine. Arterial pressure and prostaglandin excretion were not significantly correlated. In 57 patients in whom target pressure was achieved, BP before treatment was 166 +/- 2/100 +/- 1 at baseline and 144 +/- 2/86 +/- 1 mm Hg at 1 year. Excretion rates of each prostacyclin-derived product were similar before treatment and at 1 year, with no significant differences between the drugs. These findings do not support the hypothesis that deficient prostacyclin biosynthesis contributes to the pathogenesis of essential hypertension, or that increased prostacyclin biosynthesis plays a part in the response to treatment with antihypertensive medication.
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PMID:Prostacyclin biosynthesis in essential hypertension before and during treatment. 864 89


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