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

To investigate the impairment of beta-adrenoceptor responsiveness in human hypertension, we evaluated the effect of an oral salt load (400 mEq/day of NaCl for 7 days) on plasma catecholamine concentrations and beta-adrenoceptor-mediated effects in 11 young patients with mild essential hypertension. Responses of heart rate and plasma cAMP to isoproterenol administration were used as indices of beta-adrenoceptor responsiveness. Salt loading induced a significant reduction in the dose of isoproterenol required to raise the heart rate by 25 bpm (CD25) (from 7.6 +/- 1.5 to 5.3 +/- 0.9 micrograms, p less than 0.05) and an increase in the slopes of the regression lines for heart rate changes and isoproterenol doses (delta HR/IS) (from 3.3 +/- 0.6 to 4.7 +/- 0.7, p less than 0.05) and for plasma cyclic AMP (cAMP) level changes and isoproterenol doses (delta cAMP/IS) (from 0.3 +/- 0.06 to 1.4 +/- 0.3, p less than 0.05). After salt loading there was a significant reduction in plasma catecholamine concentrations with a significant relationship between changes in upright plasma epinephrine levels and changes in CD25 (r = 0.904, p less than 0.01) and in the slopes for delta HR/IS (r = 0.983, p less than 0.001) and delta cAMP/IS (r = 0.922, p less than 0.001). These results support the hypothesis that the impairment of beta-adrenoceptor sensitivity observed in human hypertension is associated with a beta-adrenoceptor overstimulation due to chronically elevated adrenergic tone.
Hypertension
PMID:Studies of the mechanisms underlying impairment of beta-adrenoceptor-mediated effects in human hypertension. 630 32

A model programme for hypertension control in the community has been implemented in North Karelia, Finland, since 1972. The treatment status of the patients was improved and blood pressure levels were reduced during 1972 to 1977. This improvement started to level off during 1977 to 1982, although more than 10% of the population aged 35-64 years were treated with antihypertensive drugs. Several analyses were done to find out which dietary factors contributed to the blood pressure level and to its change in the community. The study material consisted of random samples of the population aged 30-59 years in two counties in Eastern Finland, who participated in the surveys in 1972, 1977 and 1982. The analyses confirmed that high BMI, high fat intake, alcohol drinking and high Na intake were associated significantly with blood pressure and also with its change both in the general population and in hypertensive persons. The high levels of these nutritional factors were also associated with unsatisfactory outcome of drug treatment in the hypertensive patients. Thus, it is likely that nutritional changes that can reduce the levels of BMI, the intake of fat, alcohol, and Na would contribute significantly both to primary prevention and to the effective treatment of elevated blood pressure in the community. In Eastern Finland the levels of alcohol intake have increased both in men and women, BMI increased in men and decreased in women and serum cholesterol levels dropped both in men and women between 1972 to 1982. The results of a community-based programme to reduce salt intake in North Karelia from 1979 to 1982 confirmed that Na intake level is high in Finland. The North Karelia Salt Project showed that it is difficult to reduce salt intake at the community level during a three-year period. A slight reduction in Na intake was seen only in women both in North Karelia and in the reference area. In men Na intake did not decrease. In conclusion our results suggest that primary prevention of hypertension at the community level is not easy and that a well conceived programme for a relatively long time period is needed.
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PMID:Community-based prevention of hypertension in North Karelia, Finland. 633 24

There is a close epidemiological association between obesity and elevated blood pressure for all age groups, although not every obese individual becomes hypertensive. In populations without age-related increases in body weight, an elevation of blood pressure with age is not seen. Mechanisms included in the development of hypertension in obesity are hyperinsulinemia, insulin induced sodium retention and increased sympathetic tone. Overnutrition with over intake of sodium and lack of physical exercise contribute to the metabolic syndrome of obesity. Thus, weight reduction by decreased energy uptake and increased physical exercise is recommended in the treatment of hypertension in obese patients. The resulting fall in insulin levels may lead to decreased sodium absorption in the kidney. Although treatment of obesity by weight loss decreases blood pressure substantially, a minority of patients do not respond to the weight loss. Blood pressure generally decreases before normal weight is achieved. Salt intake reduction does not appear to explain why weight reduction lowers blood pressure. Reduced levels of plasma renin activity, serum aldosterone levels, catecholamine levels and serum insulin levels may be involved in the blood pressure lowering associated with weight loss. Since the risk of cardiovascular disease in the hypertensive patient is not only determined by the blood pressure, an overall treatment which aims at reduction of other risk factors such as glucose intolerance and hyperlipoproteinemia is advocated. Thus, in any obese hypertensive patient normalization of excess body weight and increased physical activity appears to be the first and most important step of any rational therapeutic strategy.
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PMID:Obesity and hypertension: epidemiology, mechanisms, treatment. 636 45

The diagnostic principles and current therapy employed in cases of arterial hypertension during pregnancy are summarised. Apresoline is recommended in all forms of hypertension. Salt free diets and diuretics are usually not recommended in pre-eclampsia-eclampsia. In all other hypertensive forms they are, but in association with apresoline and/or beta-blocking agents.
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PMID:[Arterial hypertension in pregnancy. Concise review]. 637 13

During the past 20 years there have been great developments in the scientific understanding of the role of nutrition in health and physical performance. Epidemiological and physiological studies have provided evidence that certain forms of dietary behaviour may be linked with an increased risk of developing disorders such as high blood pressure, coronary artery disease and some cancers. This has resulted in dietary recommendations that are intended to reduce the incidence of these disorders in the community. The science of nutrition in relation to sports performance has progressed from empirical studies investigating the effects of dietary manipulations, such as restriction and supplementation, to the direct investigation of the physiological basis of the specific nutritional demands of hard physical exercise. This review is based on the premise that it is "what comes out' rather than "what goes in', which provides the clues to ideal nutrition for athletic performance. Various aspects of the physical demands of athletic exercise are viewed as stresses that induce specific biochemical, and hence nutritional, strains in the athlete. Training is the predominant demand in the athletic lifestyle. This is characterised by acute bouts of high power output. During one hour of hard training an athlete may expend 30% of his or her total 24-hour energy output. These high power outputs have important implications for energy substrate and water requirements. Carbohydrate, specifically muscle glycogen, is an obligatory fuel for the high power outputs demanded by athletic sports. Muscle glycogen is a limiting factor in hard exercise because it is held in limited amounts, utilised rapidly by intense exercise, and fatigue occurs when it is depleted to low levels in the active muscles. Liver glycogen may also be exhausted by hard exercise and low blood glucose contributes to fatigue. High sweat rates are demanded during severe exercise and large water deficits commensurate with energy expenditure are incurred during extended periods of hard training and competition. Salt, potassium, and magnesium are lost in nutritionally significant amounts in the sweat, but vitamins and trace elements are not. Adaptive mechanisms protect athletes against electrolyte depletion. Iron loss in sweat may contribute to the iron deficiency seen in some endurance runners. Protein is degraded and amino acids are oxidised during physical exercise. Protein is also retained during muscle building training. Recent investigations indicate that the minimal protein requirements of athletes may be substantially higher than those for sedentary persons.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Nutrition and sports performance. 639 Jun 9

The effect of long-term intake of 0.6% NaCl solution on survival of Brattleboro rats, both homozygous for diabetes insipidus (DI) and heterozygous (non-DI), was investigated. Studies included whether the survival of animals could be influenced a) by the age at which the high salt intake started (either from prepuberty, i.e. from the 4th week, or after sexual maturation, i.e. from the 12th week of age); b) by uninephrectomy (UNX) which elicited hypertension in DI rats drinking saline from youth. All non-DI and those DI rats that drank saline only from adulthood, survived for the whole duration of the experimental, i.e. 14 weeks. Only 43% of animals survived in the group of DI rats drinking saline from youth. This high mortality was reduced by UNX carried out either simultaneously or 8 weeks after the onset of saline drinking. DI rats consumed several times more saline than non-DI rats. Nevertheless, the consumption was greater in the low-mortality than in the high-mortality group. Salt intake was moderately lowered by UNX. Plasma Na+ concentration was higher in rats of the high-mortality group and it was not affected by UNX. In DI rats plasma volume was greater than in non-DI rats and its values in the low-mortality group exceeded those ones of the high-mortality group. It was decreased by UNX in the low-mortality group but this was not true for the high-mortality group. It is concluded that high mortality in DI rats consuming saline from prepuberty is abolished by the intervention producing hypertension. The role of hypertension in a protection against the toxic effects of salt is discussed.
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PMID:Hypertension in Brattleboro rats and the injurious influence of salt in youth. 645 95

The mortality rates of stomach cancer and stroke were found to decrease in a similar way over a given time in different countries. The same phenomenon can be observed in Finland for both sexes. Salt is suggested to be the linking factor in the stroke-stomach cancer relationship. Recent studies indicate that salt intake in Finland is very high. Actual salt consumption levels are in Finland as high as they were in Belgium 15 years ago. The same observations can be made for cerebrovascular and stomach cancer mortality, making the salt hypothesis plausible. In contrast from 1972-73 on stroke mortality decreases faster than stomach cancer mortality. This could be observed in other western countries: USA, Austria, England and Wales, Belgium, West Germany, etc. The steeper decline may be the consequence of mass drug treatment of hypertension which started in Finland during the early years of 1970's, and also the consequence of changes in dietary habits, especially in fat intake in Finland.
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PMID:Trends in stomach cancer and stroke in Finland. Comparison to northwest Europe and USA. 647 33

Thirty-seven subjects including 29 patients with essential hypertension (8 with labile and 21 with stable disease patterns) and 8 controls received salt and water loads. Sodium chloride was administered per os at a rate of 0.12-0.22 g bw, water at a rate of 20 ml bw. Before loads the measurements were taken of the total water content in the body and of the total metabolic sodium. Radiocardiography was employed to study the central hemodynamics. After sodium chloride load BP measurements were taken over 2 h, within the first 45 min every other 5 to 10 min. Sodium excretion with urine was measured hourly, whereas the changes in the central hemodynamics were evaluated every other 5 to 10 min. After water load BP measurements were taken for 1.5 h. Urine excretions were evaluated too. It was demonstrated that patients with labile and stable hypertension responded differently to salt and water loads. In the first case the increment of BP was similar to that seen in the controls, being measured by increases in the cardiac and stroke indices. In the second case BP rises were more prolonged and more significant than in the controls and occurred primarily at the expense of the high total peripheral resistance of the blood flow. There were two types of the response to salt load: the first one involved a rapid BP elevation (after 1 to 5 min) accompanied by the violent vegetative symptomatology and BP returning to normal after 20 to 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Salt and water loads and water-sodium metabolism in patients with hypertension]. 652 12

Salt once was a scarce commodity and for some governments salt tax was an important income. The Na content of a diet without any processed foods or added salt would be approximately 400-500 mg. Food industry contributes substantial amounts of salt. A nutrition policy on Na should include regulation of the Na content in infant formulas and a decreased Na intake to reduce the risk of hypertension and possibly also gastric cancer. Iodized salt is an important source of iodine in many countries. Recommendations regarding Na intake have been given in some recommended dietary intakes and in several dietary guidelines. During the last years a few Western countries have published action programmes regarding Na and hypertension. Very few countries have standards regulating the salt content of certain products but in case any claims are made related to the Na content, this usually has to be declared. Special dietary foods with low Na content and salt substitutes are available in many countries. Standards for such products have been published by the FAO/WHO Codex Alimentarius Commission.
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PMID:Sodium in nutrition policy. 653 38

A 13-year-old white girl with severe hypertension and type IV renal tubular acidosis had decreased renal chloride clearance and exaggerated sodium chloride reabsorption by the ascending limb of Henle during hypotonic saline diuresis. Urinary prostaglandin E2 excretion was markedly diminished and often undetectable (0 to 37 ng/24 h). Treatment with oral furosemide completely reversed the hypertension and hyperkalemic acidosis, and effected a 20-fold rise in urinary prostaglandin E2. Sodium chloride reabsorption by the thick ascending limb of Henle decreased from 93.5% to 79.3%. Renal hypoprostaglandism may have a pathogenic role in this syndrome by enhancing chloride reabsorption in the ascending limb of Henle leading to extracellular fluid volume expansion, hypertension, and suppression of the renin-angiotensin-aldosterone axis. The therapeutic effects of furosemide may be partially mediated by enhancing the biosynthesis of renal prostaglandins or inhibiting their breakdown.
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PMID:Renal hypoprostaglandism, hypertension, and type IV renal tubular acidosis reversed by furosemide. 657 76


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