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

The natriuretic response was studied in anesthetized rats during the intravenous infusion of L-arginine analogues to inhibit the production of endothelium-derived nitric oxide. In an initial experimental series, rats were administered saline vehicle or vehicle containing 300 mumol/kg body wt N omega-monomethyl-L-arginine, N omega-nitro-L-arginine methyl ester, N omega-monomethyl-D-arginine, or L-arginine. Infusion of the competitive inhibitors N omega-monomethyl-L-arginine and N omega-nitro-L-arginine methyl ester significantly increased mean arterial pressure to 155 +/- 3 and 145 +/- 5 mm Hg, respectively, compared with a mean arterial pressure of 118 +/- 3 mm Hg determined in the vehicle control group. Sodium excretion averaged 3.27 +/- 1.08 and 2.52 +/- 0.78 mu eq/min in the N omega-monomethyl-L-arginine- and N omega-nitro-L-arginine methyl ester-treated rats, respectively, and each was significantly higher than the basal sodium excretion of 0.20 +/- 0.05 mu eq/min in the vehicle-treated control animals. Plasma renin activity was significantly lower in the N omega-monomethyl-L-arginine- and N omega-nitro-L-arginine methyl ester-treated groups than in the vehicle-treated group. Neither L-arginine nor N omega-monomethyl-D-arginine administration significantly altered any of the measured variables compared with vehicle alone. In a second experimental series, an adjustable snare was placed around the suprarenal aorta for the purpose of controlling renal perfusion pressure independently of increases in the systemic mean arterial pressure initiated by infusion of N omega-nitro-L-arginine methyl ester (75 mumol/kg i.v.).(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1992 Apr
PMID:Pressure natriuresis in rats during blockade of the L-arginine/nitric oxide pathway. 131 94

The renal handling of sodium and calcium in spontaneously hypertensive rats (SHR) was investigated over an extended period (10-75 weeks of age) and compared with age-matched normotensive Wistar-Kyoto controls. The animals were fed a standard rat chow except during screening periods when liquid diet that matched the pellet chow was substituted. Sodium balance, urinary excretion of sodium and calcium, fractional excretion of sodium (FENa), and renal cortical dopamine receptors (DA1 and DA2) were measured at 10, 30, 60 and 75 weeks of age. The results showed no difference between the two strains except for FENa, which was significantly higher in the SHR at 75 weeks coincident with decreased glomerular filtration rate. We conclude that a defect in renal handling of sodium and/or calcium is not a major factor in the maintenance of hypertension in the SHR.
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PMID:Long-term renal handling of sodium and calcium in spontaneously hypertensive rats. 137 67

To determine the effects of age on the responses of renin, aldosterone (PA), sodium excretion, and renal function to provocative maneuvers, we performed volume expansion and contraction in 390 normotensive and 212 hypertensive subjects in the second to seventh decades of life. The subjects were classified as Na-sensitive if their mean blood pressure was 10 mm Hg or more higher after volume expansion than volume contraction. Sodium sensitivity was associated with hypertension and increasing age. Plasma renin activity decreased with age under basal, stimulated, and suppressed conditions; the decrease was greater in hypertensives than in normotensive persons. The PA values were greater in hypertensives than in normal subjects after volume expansion. There was an age-related decrease in PA values after volume contraction in normal, but not in hypertensive, persons. With volume expansion, hypertensive persons exhibited "exaggerated natriuresis." There was an age-related increase in natriuresis in both groups; the increase was greater in hypertensives than normal subjects. Creatinine clearance decreased with age; however, the rate of decrease in this cross-sectional study was not different in hypertensive and normotensive subjects. These observations may have a bearing on why NaCl affects the blood pressures of older individuals more than younger persons.
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PMID:The influence of age on renal function and renin and aldosterone responses to sodium-volume expansion and contraction in normotensive and mildly hypertensive humans. 138 62

The behaviour of sodium transport systems across the cell membrane has been poorly investigated in elderly hypertension. Sodium efflux driven by Na+/K+/Cl-cotransport activity was therefore investigated (using a novel NMR-spectroscopy method) in 5 elderly hypertensive males (mean age 78 +/- 5 years) and 5 normotensive controls (mean age 79 +/- 3 years). In order to exclude any change in cotransport activity secondary to metabolic abnormalities, both patients and controls were non-obese and had normal glucose and lipid metabolisms. The Na+/K+/Cl-cotransport evaluation was performed after three months of pharmacological wash-out, under a diet containing 120 mEq of Na+/day. The resulting data showed that Na+ efflux due to outward Na+/K+/Cl-cotransport was higher in hypertensive group than in the normotensive one (0.50 +/- 0.10 mmol Na+/l cells/hr. vs 0.33 +/- 0.03 mmol Na+/l cells/hr., respectively, p < 0.05). Intracellular Na+ content was similar in both groups. At variance with previous data from the literature, our findings indicate that the Na+/K+/Cl-cotransport activity is elevated in elderly hypertensives.
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PMID:23Na NMR evaluation of human erythrocytes Na+/K+/CL-cotransport. A study in elderly hypertensives. 147 4

Sodium ions outflow rate through lymphocyte membranes, serum sodium, potassium, aldosterone, total catecholamines and 6-keto-PGE alpha levels, and plasma renin activity were studied in patients with mild hypertension associated with low and hugh plasma renin activity treated with captopril in a single dose of 12.3 mg and after the treatment with daily doses of 12.5 mg and 25 mg for 3 days. It was found, that captopril in hypertensive patients with high plasma renin activity decreases both systolic and diastolic blood pressure, decelerates heart rate, and decreases serum total catecholamines and plasma renin activity. Sodium ions outflow rate and serum sodium, potassium, aldosterone, and 6-keto-PGE alpha remain unchanged. Captopril in hypertensive patients with low plasma renin activity. The remaining parameters are unchanged. Moreover, it was noted that serum 6-keto-PGE alpha levels are lower in hypertensive patients with low plasma renin activity.
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PMID:[Sodium outflow rate through lymphocyte cell membranes, serum levels of sodium, potassium, aldosterone, total catecholamines, 6-keto- PGF2alpha and plasma renin activity in patients with primary arterial hypertension treated with captopril]. 148 34

Sodium balance plays a primary role in blood pressure regulation. Atrial natriuretic peptide, a recently discovered natriuretic substance, seems to participate in renal sodium handling, but its behavior in essential hypertension has not been fully defined. In our study, to avoid the "contamination" of factors other than hypertension, we evaluated the plasma levels of atrial natriuretic peptide in young men at military draft age. Our main results showed that plasma atrial natriuretic peptide levels are higher in young hypertensives with low plasma renin activity and low urinary excretion of active kallikrein. The influence of a positive genetic background for essential hypertension on plasma atrial natriuretic peptide levels was also investigated. Our data showed slightly elevated levels of the atrial hormone in young normotensives with a family history of hypertension.
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PMID:[Cardiac and renal sodium-modulating hormones in juvenile arterial hypertension. The physiopathological aspects and therapeutic results of a trial at the Policlinico Militare Celio in Rome]. 149 65

The nutritional roles, requirements, and metabolism and the quantitative relationship between dietary intakes and health for a number of the minerals and trace elements have been more clearly defined in recent years, but there are still considerable deficiencies in our understanding of these issues, e.g., the significance of calcium in the etiology and treatment of osteoporosis and hypertension. Reliable information is now available on the content, and the principal factors affecting it, of most of the minerals and trace elements in human and cow's milks. However, for some of the trace elements, there is still a wide variation in reported values in the literature, which is due, at least in part, to analytical difficulties. The contribution of cow milk and milk products to the diet in Western countries is significant for sodium, potassium, chloride, calcium, phosphorus, zinc, and iodine. Iodine is the only trace element for which there has been any suggestion of excessive amounts in cow milk. However, there is evidence of a decline in milk iodine concentrations in the United States in recent years, although the situation in other countries less clear. Breast milk usually has adequate mineral and trace element contents for feeding full-term infants, with the exceptions of fluoride, for which supplementation of infants is recommended, and of selenium in some countries, such as Finland and New Zealand, where maternal intakes are low. However, breast milk selenium contents have increased in these countries in recent years due to increased maternal selenium intakes. The concentrations of minerals and trace elements in infant formulas for full-term infants are generally higher than in human milk, and all appear to be more than adequate, with the possible exception of selenium, which may need to be increased in some formulas. Considerable changes in the mineral and trace element contents of formulas have been instituted in recent years in the light of improved knowledge of infant requirements. While the chemical forms of the macrominerals and some of the trace elements (iron, zinc, copper, and manganese) in milks are fairly well defined, the forms of many of the trace elements are unknown. Sodium, potassium, chloride, and iodine are believed to be almost totally absorbed from milks and infant formulas.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Minerals and trace elements in milk. 149 49

To determine the effects of moderate versus severe dietary sodium restriction on the development of 2-kidney, 1-clip (2K,1C) hypertension, young male Wistar rats were placed on diets containing 9, 26, or 101 (control) mumol sodium/g food. Three days later, a solid silver clip (i.d. 0.20 mm) was placed on the left renal artery and diets were continued up to 6 weeks. Adult rats received a 0.25-mm clip. In young clipped rats receiving the 101 mumol/g diet, blood pressure (BP), plasma renin activity (PRA), and BP response to captopril were increased as early as 1 week after clipping and increased further over time. Moderate sodium restriction (26 mumol sodium/g) led to only a slight delay in the development of hypertension; the levels of BP and PRA, the BP response to captopril, and the extent of cardiac hypertrophy achieved by 6 weeks were not different between the 2K, 1C rats receiving 26 or 101 mumol sodium/g. Sodium restriction to 9 mumol/g decreased rate of growth and completely prevented the rise in BP and in left ventricular weight. At 3 and 6 weeks the severely sodium-restricted rats had significantly higher PRA levels than the 2K, 1C control group. However, the BP response to captopril was attenuated relative to the other hypertensive groups. In adult rats, this level of sodium restriction had a small, but significant effect on body weight, but still prevented the increase in BP and in left ventricular weight. In conclusion, dietary sodium restriction can prevent the development of 2K,1C hypertension in both young and adult rats, but only if the restriction is severe. This effect may relate to a marked reduction in the pressor effectiveness of the renin-angiotensin system by low sodium intake per se or by associated metabolic or other changes.
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PMID:Dietary sodium restriction and the development of two-kidney, one-clip hypertension in young versus adult rats. 149 15

Diabetic nephropathy is more common in patients with a positive family history of hypertension and with elevated red blood cell sodium-lithium countertransport, a marker of risk for essential hypertension. To evaluate whether there is a relationship between this cation transport system and indicators of risk of renal and cardiovascular complications in diabetic patients before the development of clinical proteinuria, we studied 31 type 1 (insulin-dependent) diabetic patients with arterial hypertension, without clinical proteinuria and 12 normotensive normoalbuminuric diabetic patients. Sodium-lithium countertransport activity was significantly higher in hypertensive patients (0.43 +/- 0.03 mmol/l RBC x hr) than in normotensive patients (0.23 +/- 0.03; P less than 0.001). To better explore the nature of the association between this transport system and arterial hypertension, hypertensive patients were divided in two groups, with high (greater than 0.41 mmol/l RBC x hr) or normal (less than 0.41) sodium-lithium countertransport activity. The two groups of hypertensive diabetics were similar in age, sex, body mass index and blood pressure levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clustering of risk factors in hypertensive insulin-dependent diabetics with high sodium-lithium countertransport. 151 8

Erythrocyte sodium-lithium countertransport activity is increased in a subgroup of patients with essential hypertension but activity also rises temporarily during normal pregnancy. It is not known if the mechanism of raised activity is the same in both of these situations. Standard sodium-lithium countertransport activity and its kinetic characteristics (sodium affinity and maximum velocity) were measured in 15 women with a normal pregnancy. The mechanism of raised sodium-lithium countertransport activity was an increase in maximum velocity. There was no change in sodium affinity. This contrasts with essential hypertension where the mechanism is increased sodium affinity. Sodium-lithium countertransport activity was also measured in 14 primigravidae whose pregnancies were complicated by hypertension, and mean activity was not significantly higher than in normal pregnancy. However, six women had increased sodium affinity suggestive of essential hypertension and a different underlying mechanism of hypertension to those with normal sodium affinity. Prospective measurement of sodium-lithium countertransport kinetics may lead to a better understanding of the pathophysiology of hypertension in pregnancy.
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PMID:Sodium-lithium countertransport kinetics in normal and hypertensive human pregnancy. 155 43


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