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

The authors examined the activity of the antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GP) in the blood of patients with permanent essential hypertension and hypertensive crises and changes in the activity of these enzymes when monotherapy with the calcium antagonist corinfar was used. A total of 62 patients (age 52.7 +/- 0.7 years) with hypertension and 25 apparently healthy volunteers (age 43.9 +/- 0.7 years) were examined. The activity of SOD and GP was found to be decreased by 33 and 22%, respectively, in patients with permanent hypertension and by 40 and 32%, respectively, during hypertensive crises. When hypertension was treated with corinfar, the activity of COD and GP was increased by 10 and 18%, respectively. Concurrently, these patients had subjective and clinical improvement. The findings suggest that impaired lipid peroxidation makes a great contribution to the pathogenesis of essential hypertension. It can be assumed that the use of antihypertensive agents producing effects on the level of lipid peroxidation products and the enhancements of the activity of antioxidative enzymes.
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PMID:[Changes in the activity of antioxidant enzymes in patients with hypertension]. 140 12

To elucidate the role of oxygen free radicals and lipid peroxidation in the pathogenesis of early hypertension and atherosclerosis, we studied the native distribution of three primary arterial antioxidant enzymes (AEs). Specific immunohistochemical localization of superoxide dismutase (Cu-Zn SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) was examined in the arterial wall of New Zealand White rabbits: six sham-operated normotensive/normolipidemics (NT/NL), seven coarctation-induced hypertensive/normolipidemics (HT/NL), eight normotensive diet-induced hyperlipidemics (NT/HL), and six hypertensive/hyperlipidemics (HT/HL). All three AEs were confined primarily to the endothelium in NT/NL rabbit aortas. However, in HT and HL rabbits a greater proportion of the arterial wall, including the endothelium, inner media, and middle media, displayed immunolocalization of three AEs. Multiple linear-regression analysis revealed that more than 70% of the total variability in the depth of immunolocalization of arterial AEs could be explained by changes in blood pressure and/or total cholesterol. Also, levels of plasma and arterial cholesterol oxides were significantly different (p less than 0.05) in HT and HL rabbits compared with controls, with twofold increases in NT/HLs, threefold increases in HT/NLs, and fourfold increases in HT/HLs. We conclude that intense free-radical activity in the arterial wall of HT and HL animals is one possibility and that this occurs despite the presence of abundant AEs.
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PMID:Immunolocalization of native antioxidant scavenger enzymes in early hypertensive and atherosclerotic arteries. Role of oxygen free radicals. 155 32

In seven rabbits subjected to suprarenal aortic coarctation hypertension, the segments above and below the coarctation were tested for the antioxidant defences (i.e. acid-soluble thiol compounds, selenium-dependent and selenium-independent glutathione peroxidase, glutathione reductase, glutathione transferase) and thiobarbituric acid-reactive substances. Seven sham-operated rabbits served as controls. Systolic blood pressure proximal to the ligature increased significantly with respect to pre-operative values after 16 days (117 +/- 8.3 vs 71.7 +/- 5.2 mmHg, P less than 0.05), while pressure distal to the ligature remained normotensive. Higher values of acid-soluble thiol compounds, thiobarbituric acid-reactive substances and increased activities of selenium-dependent glutathione peroxidase, glutathione reductase and glutathione transferase were assayed in the suprarenal with respect to the subrenal segment in both groups. However, the values of the upper segments were more elevated in the experimental group than in controls, but no differences were observed in the lower segments. Glutathione peroxidase activity assayed with cumene hydroperoxide was higher than the activity assayed with hydrogen peroxide in the hypertensive segments, but no differences were detected in the substenotic and control segments. Furthermore, an isoenzymatic form of glutathione transferase, analogous to rat 8-8 glutathione transferase isoenzyme, was detected by immunodiffusion in the hypertensive aorta. The following conclusions may be drawn: (1) a biochemical gradient in glutathione-related enzymes, acid-soluble thiol compounds and thiobarbituric acid-reactive substances between the proximal and distal aorta seems to exist in control rabbits; (2) suprarenal aortic coarctation induces a significant increase in glutathione-related antioxidant defences and thiobarbituric acid-reactive substances of the hypertensive aortic wall.
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PMID:Aortic glutathione-related antioxidant defences in rabbits subjected to suprarenal aortic coarctation hypertension. 194 85

Clinical and experimental evidence demonstrates that hypertrophied cardiac tissue is more sensitive to ischemic injury than is normal myocardium. Recent studies indicate that cardiac ischemia-reperfusion injury involves the generation of toxic oxygen free radicals. We used the spontaneously hypertensive rat (SHR) model, with its otherwise genetically identical control (the Wistar-Kyoto [WKY] rat), to investigate the potential role of enzymes that generate and detoxify oxygen radicals in the sensitivity of hypertrophied heart to ischemia and reperfusion. Because hypertension develops progressively with age in SHRs, we assayed xanthine oxidase, superoxide dismutase, catalase, and glutathione peroxidase at three different time points and found significant fluctuations at different ages. At age 26 weeks, physiological measurements demonstrated hypertension and increased sensitivity to ischemia and reperfusion, measured as significantly decreased left ventricular recovery after injury. At this age, xanthine oxidase, which may generate oxygen radicals, was significantly increased in SHR compared with WKY rats (p = 0.003). Superoxide dismutase, which is a principal step in oxygen-radical detoxification, was significantly lower (p = 0.044). These data suggest that differences in the constitutive levels of oxygen-radical metabolic pathways are different in hypertrophied myocardium, and it is suggested that this finding may play a role in the response of these hearts to ischemia-reperfusion injury.
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PMID:Response to ischemia-reperfusion injury in hypertrophic heart. Role of free-radical metabolic pathways. 253 7

New Zealand's soil has a low concentration of selenium (Se), and its residents have a lower Se status than do most other peoples. However, New Zealanders do not suffer from the Se-responsive ills that afflict their farm animals and some people in China. New Zealanders, particularly those in the South Island, may have adapted to their low Se environment by thriftiness in urinary excretion of Se. Low glutathione peroxidase activities in their tissues have not resulted in noticeable damage or changes. The enzyme activity can be raised to a plateau by Se supplements, but there is no evidence that supplementation leads to better health. Since patterns of coronary heart disease, hypertension, and cancer in New Zealand resemble those in other Western countries, no direct link between these diseases and Se level is likely.
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PMID:Selenium in human nutrition in New Zealand. 266 24

Evidence is accumulating to suggest that selenium (Se) is an essential trace element for man and is reviewed with emphasis on those aspects peculiar to New Zealand. The extremely low Se levels in New Zealand soils results in a low Se content of foods, low dietary intakes, low urinary excretions, and low blood Se concentrations and glutathione peroxidase activities. Of these, plasma Se gives a short-term index of nutritional status while erythrocyte Se and glutathione peroxidase activities give a long-term index. The consequences of the low Se status of New Zealanders are not immediately apparent as a deficiency disease has not been detected in residents consuming a normal diet. However a Se-responsive muscular syndrome has been described in a surgical patient on total parenteral nutrition. Similar groups that might be vulnerable to a Se deficiency are children with metabolic disorders consuming synthetic protein diets, premature babies and infants during the first few months of life, and patients with cancer whose lowered dietary intake is coupled with the traumatic nature of their disease. Other groups that have been studied in relation to a possible role for Se in specific illnesses are patients with cardiovascular disease and hypertension, rheumatoid arthritis and other muscular syndromes and surgical patients with or without cancer. It is not yet possible to predict a minimum Se requirement for health but it appears that the intake of New Zealanders might be on the borderline. At present supplementation by the general population is not justified, but may be necessary for certain vulnerable groups such as patients on restricted diets. The most effective means of supplementation for increasing the Se status of New Zealanders is under study.
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PMID:Selenium in human health and disease with emphasis on those aspects peculiar to New Zealand. 676 57

Lipid peroxidation (LPO) products and activity of antioxidant defense (AOD) were evaluated in the whole blood and red cells of 78 patients with hypertension stage II given anapriline, corinfar and hypotiazid. Combined therapy with anapriline and hypotiazid (80-120 mg/day and 50 mg/day, respectively) diminishes concentrations of diene conjugates and malonic dialdehyde (MDA) in blood though LPO parameters after the treatment exceeded those of healthy subjects. Native antioxidants content and activity of antioxidant enzymes glutathione peroxidase and superoxide dismutase increased. Combination of corinfar (30-60 mg/day) with anapriline (80-120 mg/day) inhibits LPO and antioxidant defense activity to optimal leading to normalization of some LPO values and activity of antioxidant enzymes after the treatment. This combination was also effective as related to lowering of high blood pressure.
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PMID:[The lipid peroxidation indices of hypertension patients undergoing combined therapy with anaprilin, korinfar and hypothiazide]. 748 27

The incipient timing of cerebral strokes in the stroke-prone spontaneously hypertensive rats (SHRSP) was biochemically determined by investigating the relationship between the glutathione peroxidase (GSH-Px) activity in erythrocytes and the extent of stroke lesions. When the blood pressure of SHRSPs was maintained at over 240 mmHg, the GSH-Px activity fell, and the body weight also decreased. In SHRSP whose GSH-Px activity in erythrocytes had dropped below 23 units/ml of blood, the incidence of cerebral strokes was 98% (n = 88/90). The hematocrit level did not change even after the GSH-Px activity had dropped to 23 units/ml of blood. The reduced GSH-Px activity in erythrocytes observed during continued hypertension was found to be due to a decrease in GSH-Px protein, and not to any inactivation of the enzyme, as evident from immunochemical titration. At the moment when the GSH-Px activity had dropped to 23 units/ml of blood, and the control diet was changed to one based on fish or a hydralazine treatment given, the activity recovered, and an increase in body weight and prolongation of the life-span were observed. It was deduced from these findings that tracing the GSH-Px activity in erythrocytes in SHRSP would serve as an indicator for predicting and prognosing stroke lesions.
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PMID:Prediction of stroke lesions in stroke-prone spontaneously hypertensive rats by glutathione peroxidase in erythrocytes. 754 98

Previous studies have shown that exercise-induced changes in muscle antioxidant status occur shortly after exercise. The present studies were designed to determine if longer-term exercise-related changes in antioxidant enzyme activities in both normotensive (WKY) and hypertensive rats (SHR) occurred, and if these changes were related to the levels of lipid peroxidation. WKY and SHR rats were exercised over a 10-week period using a progressive treadmill regimen. After a 1-week detraining period, the animals were euthanized and measurements of tissue antioxidant enzyme activities and lipid peroxide levels were determined in both exercised and cage-sedentary groups. Decreases in antioxidant activities (particularly glutathione peroxidase and catalase) in liver, kidney, skeletal and cardiac were associated with exercise training in both WKy and SHR rats (e.g. left ventricular glutathione peroxidase specific activity in WKY rats was decreased from 234 +/- 25 [SD, n = 12] to 187 +/- 17 [SD, n = 11] units/mg protein). Elevations in activities of antioxidant enzymes were generally associated with hypertension in these tissues (e.g. left ventricular glutathione peroxidase specific activity in SHR rats was 275 +/- 30 [SD, n = 12] units/mg protein), but changes in activities were more variable than those seen in response to exercise. Exercise-related changes in tissue levels of thiobarbituric acid-reactive substances (an indirect measure of tissue lipid peroxide levels) generally did not correlate with exercise-related antioxidant enzyme activity changes, and hypertension had no effect on these levels except in liver.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antioxidant enzyme activities and lipid peroxidation levels in exercised and hypertensive rat tissues. 758 28

The effects of age and hypertension on the antioxidant defence systems and the lipid peroxidation in rat isolated hepatocytes were studied. Four different age groups (1, 3, 6 and 12 months) were considered in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Age-associated changes were observed on vitamin E status, glutathione (GSH) level, MDA formation and glutathione peroxidase (GSH-Px) activity in both strains. Maximal levels or activities of these parameters were found at 3 and 6 months, except for MDA which was low at 3 months. Then, a fall was observed at 12-month-old compared to 6-month values. In addition, GSH-Px activity was significantly lower in SHR than in WKY rats, except at the age of one month. The decrease of this enzyme activity could induce an increased cellular generation of radical species and lipid peroxidation, which might be link to hypertension.
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PMID:Age-related changes in antioxidant defence mechanisms and peroxidation in isolated hepatocytes from spontaneously hypertensive and normotensive rats. 807 5


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