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

Sodium homeostasis exerts a powerful influence on the cardiovascular system in normotensive and hypertensive animals. Previous studies indicate that factors other than blood pressure can influence cardiac hypertrophy. In the present experiments, we evaluated the effects of different sodium diets in the two-kidney, one clip hypertension model in the rat. After the renal artery had been clipped, the rats received a normal sodium (177 meq/kg), high sodium (517 meq/kg), and low sodium (7 meq/kg) diet during 4 weeks. The final blood pressure was almost the same in the three groups (normal sodium 170 +/- 12 mm Hg; low sodium 168 +/- 4 mm Hg; and high sodium 162 +/- 7 mm Hg). Sodium restriction significantly reduced the development of cardiac hypertrophy as compared with rats on normal or high sodium diets. Thus, ventricular weight and ventricular weight/body weight ratio were significantly higher in rats subjected to a normal or high sodium diet (p less than 0.01). The hypertrophied hearts of rats on normal and high sodium diets showed a larger increase in the number of cardiac beta-adrenergic receptors than those observed in hearts from low sodium diet, clipped rats. These results show that sodium modulates the development of cardiac hypertrophy in two-kidney, one clip hypertensive rats. Similarly, the cardiac beta-adrenergic receptors appear to be influenced by dietary sodium intake. A possible role of the sympathetic nervous system is suggested.
Hypertension 1990 Feb
PMID:Sodium intake modulates the development of cardiac hypertrophy in two-kidney, one clip rats. 215 29

1. Diets used to reduce sodium intake often involve changes in fats and fibre which might themselves affect blood pressure and/or lipid metabolism. To evaluate the relative importance of these dietary changes for the management of hypertension we have studied the independent and additive effects of sodium restriction (less than 60 mmol/day) and a low fat (30% energy), high P/S ratio (1.0), high fibre (30-50 g/day) 'cholesterol lowering' diet. 2. Ninety-five hypertensives entered a four group parallel study with a factorial design. Following 5 weeks familiarization subjects [BP range 109/66-168/105 mmHg] were randomly assigned to either a 'low sodium, cholesterol lowering' diet or a 'low sodium, cholesterol maintaining' diet. Half the subjects in each group were then assigned to 100 mmol/day NaCl supplement and the remainder to placebo. These diets were continued for 8 weeks. Seventy-nine of the 91 hypertensives who completed the study were on antihypertensive therapy throughout. 3. Mean urinary sodium excretion decreased from 137 (54 mmol/day (n = 43) at baseline (B) to 52 (32) mmol/day (n = 45, P = 0.0001) during intervention (I) in the low sodium groups and remained unchanged in the groups which received slow sodium (B = 129 [46], n = 43; I = 134 [29], n = 42). Diet record and plasma fatty acid analysis confirmed that the dietary aims of the study were achieved. 4. Sodium restriction reduced supine and standing systolic BP by a mean (+/- s.e.m.) of 6 +/- 2 and 6 +/- 4 mmHg, respectively (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A factorial study of fat and fibre changes and sodium restriction on blood pressure of human hypertensive subjects. 216 Mar 43

Earlier work with rat arteries has resulted in a widely held assumption that resistance artery smooth muscle will not contract on exposure to a reduced transplasmalemmal sodium gradient. In view of the well-recognized low sensitivity of rat tissue to cardiac glycosides, we have investigated the effects of altering the transplasmalemmal sodium gradient on vascular smooth muscle tone by using human resistance arteries. Incubation of arteries in low sodium or in ouabain to inhibit active sodium efflux for 1 hour increased the contractile response to caffeine stimulation; this finding indicated enhanced calcium buffering by the sarcoplasmic reticulum. Prolonged incubation in ouabain in the presence of phentolamine or diltiazem resulted in a concentration-dependent increase in the tone of resting human resistance arteries. Reduction of the transplasmalemmal sodium gradient by incubation in low sodium buffer effected an increase in tone similar to that obtained in the presence of ouabain. These results suggest that alteration of the transplasmalemmal sodium gradient may increase the vascular smooth muscle tone of human resistance arteries by altering intracellular calcium handling. This is a new finding in human resistance arteries and may involve inhibition and, indeed, reversal of sodium-dependent calcium efflux. A concentration-dependent potentiation of tone was found after the addition of ouabain to submaximally activated arteries. Sodium-calcium exchange may also play a pivotal role in this mechanism.
Hypertension 1990 Jun
PMID:Effects of ouabain and low sodium on contractility of human resistance arteries. 216 5

A total of 390 people undergoing routine examinations at the Portes Center, a screening center in Chicago, and at the Northwestern Memorial Hospital employee health service, underwent an in-depth battery of tests designed to explore the relationships of both intracellular erythrocyte sodium and sodium-lithium countertransport with age, race, gender, body mass index, pattern of alcohol intake, exogenous hormone use and the presence of hypertension. Erythrocyte sodium was significantly higher in blacks than in whites and in men than in women aged 20-39 years. Relationships of erythrocyte sodium with race and gender, as well as inverse associations with alcohol intake in men, and positive associations with age and the presence of hypertension in women were significant on multivariate analysis after control for other variables. Sodium-lithium countertransport was significantly higher in whites than in blacks and in men than in women aged 20-59 years. Associations of sodium-lithium countertransport with race and gender as well as positive associations of sodium-lithium countertransport with body mass index in men and women were significant on multivariate analysis after control for other variables. Age-related gender differences in both sodium-lithium countertransport and erythrocyte sodium, as well as the association of erythrocyte sodium with the presence of hypertension in women but not in men, suggest a hormonal interaction with sodium transport in the development of hypertension.
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PMID:Hypertension and sodium transport in 390 healthy adults in Chicago. 216 74

1. Sodium-lithium countertransport activity in a standard assay, its sodium affinity constant and maximum velocity were measured in erythrocytes from normal subjects and from essential hypertensive patients with and without a family history of hypertension. 2. In normal subjects the sodium concentration used in the standard assay was similar to the sodium affinity constant so that the activity measured in this assay was less than the maximum velocity. 3. In patients with essential hypertension and a positive family history, 33% had a sodium-lithium countertransport activity greater than the upper limit of the normal control range (0.4 mmol of Li+ h-1 l-1 of cells). 4. The reason for the raised sodium-lithium countertransport activity was an increased sodium affinity (lower sodium affinity constant) at the outside ion-binding site. 5. Of the patients with essential hypertension and a positive family history but sodium-lithium countertransport activity within the normal range in the standard assay, 30% also had a low sodium affinity constant. 6. A low sodium affinity constant at the outside site of the sodium-lithium countertransporter may be a more specific indicator for a group of patients with inherited hypertension than the standard sodium-lithium countertransport activity assay.
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PMID:Increased erythrocyte sodium-lithium countertransport activity in essential hypertension is due to an increased affinity for extracellular sodium. 217 57

Moderate salt restriction is of debatable efficacy in the treatment of mild or moderate hypertension; however, salt restriction enhances the activity of most antihypertensive drugs. Some observations suggest that the antihypertensive activity of calcium antagonists is not increased or could even decrease with dietary salt restriction. In the present work 15 patients suffering arterial hypertension and normal renal function are studied during four two week periods; a) unrestricted diet and medication, b) unrestricted diet and nifedipine (40 mg/day), c) low salt diet (5 g of salt/day) and nifedipine, and d) the same low salt diet, nifedipine and a salt supplement (6 g/day); salt or placebo were given in a double blind manner. At the end of each period arterial blood pressure was recorded, a urine sample for sodium determination was taken, and a blood sample was drawn for serum renine activity and biochemical parameters; at the end of each period patients' weight was recorded. Blood pressure significantly decreased (systolic: 9.83%, and dyastolic 11.17%) in patients treated with nifedipine, with no differences observed with salt modifications. Urinary sodium reflected correctly dietary salt modifications. Serum renine activity significantly increased during salt restriction. No significant changes were observed in weight or in the biochemical parameters studied. These results seem to suggest that the antihypertensive effect of nifedipine in patents suffering mild to moderate essential hypertension, with no change observed is not altered by the amount of salt in diet, at least within the limits studied (89.7 to 190 mEq/day of Sodium).
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PMID:[Effect of moderate salt restriction on the antihypertensive action of nifedipine: a double blind study]. 218 65

Spontaneously hypertensive rats have reduced peripheral insulin sensitivity. To determine whether hypertensive rats demonstrate reduced response to the antinatriuretic effect of insulin, urinary sodium excretion was determined in hypertensive and normotensive rats (n = 7 per group) before and during euglycemic insulin administration at two infusion rates (21 milliunits/kg load and 4 milliunits/kg/min or 85 milliunits/kg load and 8 milliunits/kg/min). Hypertensive and normotensive time controls received the vehicle for insulin administration. Mean arterial pressure was greater (p less than 0.05) and inulin clearance was less (p less than 0.05) in hypertensive than normotensive rats before insulin infusion. Baseline fractional sodium excretion was not different between groups. Low dose insulin infusion reduced (p less than 0.05) fractional sodium excretion from 0.81 +/- 0.43% to 0.31 +/- 0.07% in hypertensive rats and from 1.05 +/- 0.37% to 0.47 +/- 0.18% in normotensive rats. High dose insulin infusion reduced (p less than 0.05) fractional sodium excretion from 0.67 +/- 0.22% to 0.21 +/- 0.08% in hypertensive rats and from 0.81 +/- 0.15% to 0.30 +/- 0.09% in normotensive rats. Sodium excretion was unchanged in time controls. The reduction in sodium excretion was similar in both rat groups during low dose and high dose insulin infusions. Mean arterial pressure and inulin clearance were unchanged from baseline values during insulin infusion in all rat groups. Glucose requirement to maintain euglycemia was greater (p less than 0.05) in normotensive than hypertensive rats at both insulin infusion rates. Thus, while hypertensive rats have reduced sensitivity to the hypoglycemic effects of insulin, the antinatriuretic response to insulin is not different from that of normotensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1990 May
PMID:Effect of insulin on renal sodium handling in hypertensive rats. 218 52

Mild hypertension is very common, 50% of hypertensives being with their diastolic BP between 90 and 104 mmHg. Many large studies, especially HDFP, had shown not only the deleterious cardiovascular effects of mild hypertension but also the benefits obtained with the therapy. The non-pharmacological approach should be the first step in the treatment of mild hypertension. Isolated systolic hypertension have a high prevalence in the elderly, increasing the cardiovascular morbidity and mortality. Sodium restriction and, if necessary, vasodilators increasing the arterial compliance seem to be the logical approach to treat isolated systolic hypertension. Finally, eclampsia is the most serious complication of pregnancy - induced hypertension. The treatment with bed rest and either betablockers or methyldopa is beneficial. If eclampsia occurs hydralazine, magnesium sulphate or nifedipine should be used.
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PMID:[Arterial hypertension in special situations: mild, systolic and in pregnancy]. 218 54

Using the technique of differential plaque filter hybridization, a rat cDNA was isolated whose corresponding gene expression in the kidney was positively modulated up to threefold by sodium depletion. This mRNA was more abundantly expressed in the kidneys of 17-week-old spontaneously hypertensive rats than those of age-matched Wistar-Kyoto rats. The putative protein encoded by this cDNA is a homologue of cyclophilin, a cytosolic binding protein for cyclosporin A. This cyclophilin-like protein mRNA was expressed in all the tissues examined, including the adrenal, atrium, brain, kidney, liver, lung, spleen, and ventricle. Sodium depletion in rats increased the expression level of this mRNA not only in the kidney but also in the liver. The administration of cyclosporin A in rats increased the expression level of this mRNA in the kidneys and livers. By virtue of its possible involvement in sodium homeostasis and its homology to cyclophilin, this molecule might have significant implications in the mechanism of cyclosporine-induced renal insufficiency and hypertension.
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PMID:Molecular cloning of a complementary DNA to rat cyclophilin-like protein mRNA. 219 66

The effect of long-term oral sodium loading on blood pressure and on stress-induced cardiovascular response was studied in normotensive and marginally hypertensive young adults. The 121 subjects, 18-23 years old, included 38 whites and 83 blacks. Blood pressure and heart rate response to the stress of mental arithmetic was measured before and after 14 days of sodium load, which consisted of 10 g NaCl/day added to the usual diet. A sodium-sensitive response to sodium load occurred in 18.4% of whites and 37.3% of blacks. Sodium-insensitive subjects had a higher rate of sodium excretion (p less than 0.001). Sodium-sensitive hypertensive subjects had a significantly greater weight gain (p less than 0.001). A significant correlation between blood pressure change and sodium excretion (r = -0.28, p less than 0.01) occurred in the sodium-sensitive group. The high sodium intake did not augment the blood pressure or heart rate response to the beta-adrenergic-mediated stimulus of mental arithmetic in the population when grouped by blood pressure, race, or sodium sensitivity. These results suggest that blood pressure increase in response to sodium load, particularly in blacks, is related to functional changes in peripheral vascular resistance.
Hypertension 1990 Jan
PMID:Effect of chronic sodium loading on cardiovascular response in young blacks and whites. 229 13


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