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

The importance of salt and water in the pathophysiology of the hypertensive state is well recognized. The current study is the first to report simultaneous measurements of red blood cell mass, plasma volume, extracellular fluid and total body water levels. Studies were performed in 82 white men, 14 with normal blood pressure and 16 with low renin and 52 with normal renin hypertension. The results indicate that subjects with normal renin hypertension compared with age-matched controls are characterized by an absolute increase (1.5 liter/m2) in intracellular fluid (total body water minus extracellular fluid). Furthermore, the ratio of extracellular fluid to total body water is decreased (0.43 to 0.38). No volume differences were found between subjects with low renin hypertension and age-matched subjects with normal renin hypertension. We conclude that subjects with normal renin hypertension compared with age-matched peers are characterized by an expanded intracellular fluid and that subjects with low renin hypertension do not exhibit a unique volume disorder.
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PMID:Volume studies in men with mild to moderate hypertension. 49 11

Studies of 16 adults with nephrotic edema reveal a spectrum of disease, the extremes of which suggest two different pathophysiologic forms. Patients with the "classic" form--vasoconstriction or hypovolemic nephrosis--have high renin and aldosterone levels that are stimulated rather than suppressed by salt-loading but become lower before steroid diuresis. These patients have minimal lesion disease and, perhaps from diffuse capillary damage, tend to have hypovolemia with renin-induced vasoconstriction. Patients with the second, and heretofore undescribed, form--hypervolemic or overfilling nephrosis--have low renin and aldosterone values that rise normally after sodium depletion. Hypertension, mild renal insufficiency, hypervolemia, and steroid resistance with chronic glomerulonephritis are seen histologically. This form appears volume overloaded from impaired renal sodium excretion. In remission of either type, renin system deviations tend towards normal, but one form does not convert to the other. Renin-sodium profiling may help reveal the two forms and predict steroid responsiveness.
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PMID:Nephrotic syndrome: vasoconstriction and hypervolemic types indicated by renin-sodium profiling. 49 1

The effects of d,l-alpha-tocopheryl nicotinate (EN) on model hypertension in rats were studied in comparison with d,l-alpha-tocopheryl acetate (EA). The progress of hypertension in young SHR during the 9th to 15th weeks after birth was markedly accelerated by replacing their driking water with 1% saline. The highly-developed hypertension in old SHR (9 months of age) was further advanced by salt-loading. Oral administration of 20 or 100 mg/kg of EN or 88 mg/kg of EA, once a day, delayed the progress of hypertension in young SHR and reduced advanced hypertension in old SHR. An antihypertensive effect of tocopheryl esters was also found in DOCA-salt hypertensive rats. The treatment with EN or EA definitely reduced the incidence of pathological changes accompanying model hypertension such as suppressed weight gain, pulmonary edema, myocardial fibrosis, cerebral hemorrhage and protected the animals from death. In antihypertensive effect, EN was about 5 times more active than EA in molecular base, and the effects of EN protecting from pathological changes associated with model hypertension were more definite than those of EA. The treatment with EN or EA reduced water and sodium retention in the DOCA-salt hypertensive animals. This fact may suggest the implication of a mechanism through electrolyte metabolism in the antihypertensive action of these tocopheryl esters.
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PMID:Antihypertensive action of d,l-alpha-tocopheryl nicotinate in rats. 50 48

Plasma catecholamine levels have been used experiemtally and clinically as the indices of the sympathetic nerve activity. We measured plasma catecholamines using high pressure liquid chromatography in rats to assess the significance of plasma catecholamines as an index of the sympathetic nerve activity and its role in hypertension. Pentobarbital anesthesia depressed plasma catecholamine levels, especially plasma adrenaline. Sodium loading for 5 weeks suppressed plasma noradrenaline, while administration of furosemide (1 mg/kg) produced the elevation of plasma noradrenaline. Experimental hypertension, one-kidney and two-kidney types of Goldblatt hypertension and DOCA-salt hypertension, raised plasma noradrenalines both in acute and chronic phases. The infusion of pressor doses of angiotensin II suppressed plasma noradrenaline by the reflex mechanism. Sar1, Ile8-angiotensin II and SQ 14,225 did not suppress plasma cathecholamine elevation due to hemorrhage. L-Hydroxyldopamine produced elevation of plasma catecholamines in experimental nypertension and controls in rats. After adrenal demedullation, plasma noradrenaline was decreased by the administration of 6-hydroxy-dopamine. Acute reduction of circulating blood volume and blood pressure fall produced the elevation of plasma catecholamine, especially plasma adrenaline. In rats, the adrenal medulla plays an important role in the regulation of blood pressure.
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PMID:Plasma catecholamines determination using high pressure liquid chromatography and their roles in blood pressure regulation and experimental hypertension in rats. 50 4

The activity of the adrenaline-forming enzyme, phenylethanolamine-N-methyltransferase (PNMT) and the levels of the catecholamines dopamine, noradrenaline and adrenaline were determined during the development of the DOCA-salt hypertension in selective areas of the rat brain stem and hypothalamus. Increases in PNMT activity were restricted to the A1 area and locus coeruleus after 2 weeks of DOCA-salt treatment and were extended to the A2 area after 9 weeks of treatment. Adrenaline concentrations were higher in these areas only after 9 weeks of treatment. Noradrenaline levels did not change, except in the nucleus tractus commissuralis. Dopamine levels were unchanged at all times and in all structures studied. These results implicate brain stem adrenaline neurons in the central response which occurs during the DOCA-salt experimental hypertension.
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PMID:Brain catecholamines during development of DOCA-salt hypertension in rats. 50 25

The populations of the developed nations of the world exhibit an increase in blood pressure with age, while in primitive societies blood pressure remains relatively constant throughout adult life. Hypertension may be a complex of diseases all having the same clinical manifestations but not being caused necessarily by the same factors. A possible common denominator in the development of any chronic elevation of blood pressure is the need for the kidney to increase urine volume to promote sodium excretion and, thereby, prevent a chronically expanded extracellular fluid (ECF). Hypertension may be viewed as a maladaptation of the body in its attempt to maintain homeostasis of the ECF. Man evolved under conditions of relative scarcity of salt and even now can maintain normal body function with an intake of less than 2 g/day. The high risk person appears to have a hereditary predisposition to a rise in blood pressure in the presence of a high sodium (NaCl) intake. Actually, the degree of rise in blood pressure may be an interaction between the amount of genetic predisposition and the level of sodium and its relation to potassium intake. Recent work in two Massachusetts communities supports this interpretation and suggests that differences in blood pressure distribution may increase with age between a higher and lower sodium community.
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PMID:Age as a function in the development of sodium-related hypertension. 51 Feb 40

It is shown that various types of vessels (elastic, musculo-elastic, and muscular) possess initially different capacity for synthesizing and destroying prostaglandins. Under the effect of indomethacin and salt load considerable changes occur in the synthesis and metabolism of prostaglandins and the closely related system of cyclic nucleotides in the vessels of experimental animals. The character of these changes suggests the predominance of constrictive vascular reactions, which was confirmed by the results of functional tests on segments of the aorta and femoral arteries. It was shown also that the walls of small arteries of different organs, the kidneys in particular, undergo marked structural changes resulting in their thickening and narrowing of the lumen. These functional and structural changes may underlie the increase in peripheral vascular resistance and be the principal pathogenic mechanism of hypertension.
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PMID:[State of the vascular wall in experimental hypertension induced by the administration of indomethacin in combination with a saline drink]. 51 75

Around the turn of the century it was observed that low dietary salt consumption is frequently associated with reduction in blood pressure in essential hypertension. It has not been established whether this is a specific effect of NaCl or whether it is an unspecific consequence of the weight loss frequently accompanying low salt intake. Changes of the Renin-Angiotension-Aldosterone system do not seem overly important for the understanding of the original lesion in essential hypertension. Hemodynamic studies demonstrate that increased peripheral (arterial) resistance is characteristic for the disease. It was possible to breed a rat strain with an "anlage" for hypertension which could be unmasked by salt supplements. In humans, essential hypertension is associated with increased salt preference suggesting a genetic factor. This increased desire for salt induces a high salt content of the body including the arterial wall. The hypothesis is being discussed that the stimulating effect of NaCl leads to contraction of the arterial wall inducing increased peripheral resistance - the hallmark of essential hypertension.
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PMID:[Sodium chloride and hypertension (an additional, temporary hypothesis)]. 52 31

22 patients (4 female, 18 male, mean age 47 +/- 10.7 years) with severe essential hypertension (n = 21) and renovascular hypertension (n = 1) were treated with a mean daily dosage of 16.3 +/- 5.1 mg minoxidil for up to 42 weeks. In addition, all patients received a diuretic (hydrochlorothiazide or furosemide) and a beta-blocker (pindolol or propranolol). 8 patients were treated simultaneously with alpha-methyl-dopa. Within one week minoxidil led to a significant reduction in both systolic and diastolic supine blood pressure (p less than or equal to 0.005) from 201.3 +/- 29.0/125.4 +/- 19.2 mm Hg to 172.8 +/- 28.3/106.0 +/- 19.9 mm Hg. The maximum initial blood pressure response was observed after 3 weeks with a mean daily dosage of 12.2 +/- 9.4 mg of minoxidil (160.5 +/- 20.7/99.4 +/- 13.8 MM Hg, p less than or equal to 0.001). Throughout the remaining period a constant and significant reduction in supine systolic and diastolic and upright diastolic blood pressure was achieved (p less than 0.005-less than 0.001) whereas at times systolic blood pressure values could not be lowered significantly. Body weight and pulse rate showed no significant changes throughout the study. In some cases furosemide had to be added by up to 500 mg/day to counteract minoxidil induced water and salt retention. Only moderate doses of beta-blockers were required to prevent a drug induced rise in pulse rate. In these patients a significant change in renal function was not observed. The results show that minoxidil is a potent drug in the treatment of severe essential hypertension.
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PMID:[Minoxidil in treatment resistant hypertension]. 53 65

1. Basal levels of pulse rate, blood pressure and rates of sodium and potassium excretion were observed in eight white male patients with mild hypertension and eight age-, sex- and colour-matched controls during an initial rest period of 90 min and then for 5 h after a 1 h period of isometric exercise involving all four limbs in rotation. The studies were repeated on another day with the subjects resting instead of exercising for 1 h. 2. Changes in systolic pressure after exercise were similar in the hypertensive and control groups, whereas the rise in diastolic pressure was higher and the rise in pulse rate lower after exercise in the hypertensive group compared with the control group. 3. The changes in the rate of salt excretion were significantly different in the two groups, the hypertensive group retaining proportionately more sodium and potassium over several hours.
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PMID:Effect of isometric exercise on the renal excretion of sodium and potassium in mild hypertension. 54 Apr 48


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