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

The peptides angiotensin II (ANGII) and atrial natriuretic factor (ANF) regulate blood pressure and salt and water balance by producing antagonistic physiological effects in a variety of tissues. We used in vitro autoradiography with [125I] ANGII and [125I]ANF to compare receptor regulation for both peptides in various tissues in three experimental models of hypertension [two-kidney, one-clip (2K-1C); one-kidney, one-clip (1K-1C); desoxycorticosterone-salt (DOCA-SALT)] and three nonhypertensive control groups [two-kidney (2K-CON); one-kidney (1K-CON); salt-loaded (SALT-CON)]. Blood pressures at death were significantly higher in all three hypertensive groups compared to those in normotensive controls, but there were no significant differences among the hypertensive or normotensive groups, respectively. PRA was highest in the 2K-1C group and lowest in the DOCA-SALT and SALT-CON groups, but plasma ANF levels did not differ significantly among the hypertensive or normotensive groups. In the aorta, ANGII receptor binding was decreased in 2K-1C rats and increased in DOCA-SALT and SALT-CON rats; ANF receptor binding was moderately increased in all three hypertensive groups. Adrenal zona glomerulosa binding for ANGII was highest in the 2K-1C group and lowest in DOCA-SALT rats, while ANF binding was decreased in DOCA-SALT and SALT-CON animals. ANGII renal glomerular binding was increased in DOCA-SALT and SALT-CON groups, and ANF glomerular binding was decreased in the same two groups. In the brain, the subfornical organ showed increased binding for both ANGII and ANF in DOCA-SALT rats. Our results show that tissue receptor binding of ANGII and ANF is regulated in distinct patterns in different models of hypertension, and that these patterns are tissue specific and more complex than simple reciprocal regulation.
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PMID:Angiotensin II and atrial natriuretic factor-binding sites in various tissues in hypertension: comparative receptor localization and changes in different hypertension models in the rat. 254

The effects of prolonged (30 day) treatment with daily therapeutical doses of cyclosporine A (CSA) (20 mg/kg) on the function and morphology of adrenal cortex were studied in adult male rats. CSA-treated animals developed a notable hypertension, along with a striking rise in PRA, which was not coupled with significant changes in the plasma concentrations of aldosterone and corticosterone (hyperreninemic hypoaldosteronism). Morphometry showed that zona glomerulosa (ZG) and zona fasciculata, and their parenchymal cells were atrophic. Isolated capsular (ZG) and inner (zona fasciculata/reticularis) cells displayed reduced basal and stimulated secretory responses. However, while the response of ZG cells to angiotensin II was almost completely suppressed (96%), basal steroid secretion of isolated cells, as well as the aldosterone and corticosterone response of ZG cells to potassium and ACTH, and corticosterone production of inner cells in response to ACTH were decreased by only about 30-40%. The hypothesis is advanced that CSA exerts a dual effect on rat adrenal cortex: 1) a general inhibitory effect on the growth and steroidogenic capacity of adrenocortical cells, which manifests itself only after very prolonged treatment and may be caused by an impairment of protein synthesis; and 2) an acute effect involving the specific blockade of the angiotensin-II-induced stimulation of the secretory activity of ZG cells.
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PMID:Effects of prolonged cyclosporine-A treatment on the morphology and function of rat adrenal cortex. 254 84

Plasma from 37 essential hypertensive patients, from 11 subjects with primary aldosteronism and from 23 normotensive subjects was tested for ouabain-like activity. Despite a very substantial overlap, hypertensive patients (both essential and secondary) showed significantly higher levels of a ouabain-like plasma factor compared to normotensive controls. No substantial differences could be detected, however, between the two forms of hypertension; in particular, no significant changes were observed in the low-PRA subgroup. Our results are hardly compatible with the hypothesis that this substance may be of crucial importance in the development either of essential hypertension or of primary aldosteronism.
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PMID:Plasma ouabain-like activity in essential hypertensive patients and in subjects with primary aldosteronism. 255 4

Adrenal cysts are rare, but they have been disproportionately associated with hypertension. This report describes a hypertensive patient with increased levels of 19-nor-deoxycorticosterone (19-nor-DOC), a potent mineralocorticoid. The patient was a thirty year old man with hypokalemia, moderately severe hypertension, suppressed PRA, and low aldosterone secretion. Following surgical removal of a 10 cm adrenal cyst, the hypertension improved, the hypokalemia resolved, and the PRA and the aldosterone secretion normalized. Urinary 19-nor-DOC pre-op was elevated 4.6 microgram per day (normal less than 1.0 microgram/day and subsequently became normal at 0.7 microgram per day following surgery. The adrenal cyst was a fibrous walled structure containing mucinous straw-colored fluid. Pericystic adrenocortical tissue demonstrated increased 19-OH-DOC production (a 19-nor-DOC precursor) which may have been responsible for the 19-nor-DOC excess. We hypothesize that compressive adrenal damage from the cyst may produce a form of adrenal regeneration hypertension which is known to be associated with 19-nor-DOC excess.
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PMID:An adrenal cyst associated with 19-nor-deoxycorticosterone excess and low renin hypertension. 265 Sep 31

Severe dietary sodium restriction initiated early in life is required to prevent development of hypertension in spontaneously hypertensive rats (SHR). Moderate sodium restriction does not affect hypertension development. This relative insensitivity to sodium restriction may be related to compensatory increases in other pressor mechanisms, specifically the renin-angiotensin system. We evaluated this possibility by measuring plasma renin activity, the blood pressure response to the angiotensin converting enzyme inhibitor captopril as well as blood pressure responsiveness to exogenous angiotensin II in SHR and Wistar-Kyoto rats (WKY) raised from birth until 6 or 16 weeks on control (101 mumol Na+/g food), moderate (26 mumol/g) or two severe (17 or 9 mumol/g) sodium-restricted diets. Moderate sodium restriction did not affect development of hypertension, but also did not cause significant increases in PRA or the blood pressure response to captopril in SHR or WKY. In contrast, severe sodium restriction blunted or prevented the development of hypertension in SHR and was associated with (1) marked increases in plasma renin activity (2) increased maintenance of blood pressure by the renin-angiotensin system (as assessed by captopril), and (3) a marked decrease in the blood pressure response to angiotensin II. We conclude that the relative insensitivity of hypertension development in SHR to dietary sodium restriction does not relate to a compensatory increase in the activity of the renin-angiotensin system. The moderate sodium restriction employed (26 mumol/g) may rather represent the lower end of the normal range.
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PMID:Dietary sodium restriction and the renin-angiotensin system in young spontaneously hypertensive rats. 265 16

The physiological role of inactive renin, especially the question of whether and how a conversion to active renin takes place in vivo, remains controversial. In order to show the dynamic alterations from inactive to active renin following acute ACE-inhibition, both forms of renin were investigated in both renal veins and the peripheral circulation of 20 patients with essential hypertension and 20 patients with renovascular hypertension before and 1 h after 25 mg of captopril. Active and inactive renin were determined indirectly as plasma renin activity (PRA, unit: ng/ml x h). In vitro activation of inactive renin was achieved with trypsin (1 mg/ml plasma), followed by a further determination of PRA (= total renin). Subtraction of the active renin from the total renin yields the amount of inactive renin. In patients with essential hypertension, the mean values of active renin increase equally in both renal veins (1.4 and 1.3 before, 1.9 and 1.8 after captopril) and the peripheral circulation (0.9 and 1.3) (p less than 0.002), whereas the inactive renin decreases correspondingly. Renal veins: 7.6 and 8.2 before, 7.2 and 7.6 after captopril; peripheral circulation: 7.7 before and 7.0 after captopril (p less than 0.05). In all patients with renovascular hypertension, there is basally a marked lateralization of active renin (6.4 vs 3.5; p less than 0.01) and inactive renin (20.5 and 18.9, p less than 0.03) towards the side of the ischemic kidney. After captopril, the values for total renin and active renin increase (p less than 0.001), and the side difference for active renin becomes still more pronounced (33.0 vs 14.2; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Conversion of inactive renin to active renin following acute angiotensin converting enzyme inhibition in essential hypertension and renovascular hypertension]. 265 7

To evaluate the activity of sympathetic system and of plasm renin in elderly patients with borderline (BH) and established essential hypertension (EH), 31 BH mean age 38 years and 30 EH, mean age 39 years; 15 BH, mean age 66 years, and 15 EH, mean age 68 years, were studied at rest and after dynamic exercise. At the same time blood pressure and heart rate were automatically recorded, while blood samples were collected for PRA and plasma epinephrine (E) and norepinephrine (NE) assays. Plasma E levels showed no significant differences between the groups examined at rest. Nevertheless, young BH had higher plasma E levels than young EH after stress and elderly BH showed plasma E levels higher than age-matched EH in response to dynamic exercise. The PRA behaviour was similar among all the groups, but dynamic exercise induced a greater increase in BH than in EH. Moreover, the stress-induced increase in plasma NE levels was higher in EH than in BH. Our results demonstrate in old BH, as well as in young BH, a response of E to stress greater than in the age-matched EH. In our study BH, both young and old subjects, seem to be characterized by a sympathoadrenal overactivity pointed out by an excessive release of E from the adrenal gland after stress. This exaggerated sympathoadrenal reactivity may constitute an important mechanism in triggering hypertension independent of age.
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PMID:Epinephrine and norepinephrine pattern in elderly patients with borderline and established hypertension. 266 50

Twelve hypertensive patients (mean age 46.6 years, range 37-55 years) with fibromuscular dysplasia of the renal artery were treated with percutaneous transluminal renal angioplasty (PTRA) and the effects on the renin-angiotensin-aldosterone system and blood pressure were studied in the acute phase. The technical result of PTRA measured by angiography and reduction of PRA and aldosterone excretion was satisfactory in 11 patients. In spite of this only three patients were cured of their hypertension and two patients were improved at six months follow-up. During PTRA an immediate rise in plasma renin activity was noted in patients without beta-receptor blockade but not in patients treated with beta-receptor blocking agents suggesting a beta-receptor mediated release. This peak in renin release was not accompanied by any rise in systemic blood pressure. The blood pressure response in the acute phase did not show any regular pattern. We conclude that PTRA can serve as a model for studying effects of 'clamping' and 'declamping' of the renal artery in man.
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PMID:Percutaneous transluminal renal artery dilatation for fibromuscular dysplasia with special reference to the acute effects on the renin-angiotensin-aldosterone system and blood pressure. 293 4

Percutaneous transluminal renal angioplasty (PTRA) has been infrequently used in the treatment of children with hypertension due to renal artery stenosis. We report our results in five patients aged 4 to 22 years with hypertension diagnosed at ages 1 1/2 to 10 years. Four of the five patients had been on antihypertensive medication prior to angioplasty. Four had fibromuscular disease and one had probable Takajasu's arteritis; two had solitary kidneys. Following angioplasty, a prompt decrease in blood pressure was observed in all patients. Further, four of five patients after PTRA were normotensive without antihypertensive medications, and in all PRA declined. PTRA can be a safe and effective alternative to surgical treatment in the management of renovascular hypertension in childhood. We suggest that PTRA should be the first procedure attempted to correct renovascular hypertension in children.
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PMID:Evaluation of percutaneous transluminal renal angioplasty in childhood hypertension. 293 92

To assess the diagnostic and prognostic value of renal venous renin levels in renovascular hypertension, 95 patients with severe unilateral renal artery stenosis were studied. Surgery (n = 52) or percutaneous transluminal dilation (n = 43) were done irrespective of renal venous renin levels. Lateralization of renin secretion as assessed by the PRA ratio and the renin secretion index was found in the majority of patients (66% and 88%, respectively). Patients with fibromuscular hyperplasia had more frequently PRA ratios less than 1.5 than those with arteriosclerotic stenosis (p less than 0.05). The renin secretion index proved to have a higher sensitivity (92%) and predictive value (92%) for a successful outcome of both surgery and PTA than the PRA ratio (69% and 89%, respectively), while the specificity was the same with both parameters (42% and 43%, respectively). The contralateral suppression index was most specific in predicting an unfavorable outcome. However, with all ratios used, a considerable number of false-negative and false-positive tests were observed both with surgery and PTA, a finding limiting the value of the method in selecting patients for these interventions. Other factors, such as age of the patient, kidney function and the underlying arterial disease turned out to be equally important prognostic factors. Thus, although cure after both surgery and PTA is more likely in the presence of lateralized renin secretion and contralateral suppression, the method does not allow to exclude patients with severe renal artery stenosis, hypertension and negative renal venous renin tests from these interventions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal venous renin determinations in renovascular hypertension. Diagnostic and prognostic value in unilateral renal artery stenosis treated by surgery or percutaneous transluminal angioplasty. 294 11


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