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

A 16-month-old black male infant had unusual thirst, polyuria, hyponatremia, and hypertension. His polyuria was unresponsive to vasopressin therapy, and his high blood pressure was not effectively controlled by antihypertensive drugs. Radiographic examinations revealed an occult Wilms tumor in the right kidney. After removal of the tumor, the signs and symptoms were relieved. The tumor had a renin activity about 280 times that of the adjacent renal cortex, and many intracytoplasmic secretory granules were found on electron microscopy. The pathogenesis of these clinical manifestations appears to be mediated through the physiologic pathways of renin-angiotensin II and renin-aldosterone.
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PMID:Polydipsia, polyuria, and hypertension associated with renin-secreting Wilms tumor. 20 43

Plasma renin activity (PRA) was measured in 14 control subjects and 27 patients with essential hypertension (EH) (low renin group: 9, normal renin group: 11, and high renin group: 7) before and after the following stimulation tests. Test procedures: 1) Circadian rhythm (0600, 1600 and 2400h). 2) Adrenal stimulation test (ACTH: 12.5 I.U.). 3) Adrenal suppression test (Dexamethasone: 1.0 mg). 4) Metopirone test (1.5 g). 5) Angiotensin II infusion test (8 ng/kg/min). 6) Saline infusion test (1000 ml/hr). Patients with low PRA showed significantly lower levels of PRA than those of other two groups in circadian rhythm, after 2 hours of ACTH infusion and after angiotensin II infusion. Furthermore, these patients showed significantly higher responses of PRA than other two groups after furosemide test under dexamethasone and after metopirone test. In case of saline infusion test, patients with low and normal PRA did not show significantly decreased levels of PRA after the infusion, though all patients with high PRA and all control subjects showed significantly decreased levels of PRA. From the present studies, it might be concluded that patients with low PRA has an unknown mineralocorticoid excess which is ACTH dependent and 11 hydroxylated and some of hypertensive patients have an abnormality in their renin-angiotensin-aldosterone volume feed back loop as a factor for hypertension.
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PMID:Pathogenesis of essential hypertension with low renin: responses of plasma renin activity to various stimulation tests in essential hypertension. 21 18

Hypertension in 17 alpha-hydroxylase deficiency was studied by comparing it with hypertension in Cushing syndrome or that in primary aldosteronism. Furthermore, the role of endogenous increases of ACTH, deoxycorticosterone, and 18 alpha-hydroxy-deoxycorticosterone upon blood pressure was studied in rats by administerating metopirone. Hypertension in 17 alpha-hydroxylase deficiency was considered to be more similar to that in primary aldosteronism from the studies on renin components, pressor responses to angiotensin II and norepinephrine, and renin responses to stimulations. Plasma catecholamines were slightly decreased in 17 alpha-hydroxylase deficiency. The hypertension was alleviated by the administeration of dexamethasone in 2 of 3 patients with 17 alpha-hydroxylase deficiency. However, in the remaining one who had an accelerated hypertension and normal renin, the hypertension was not alleviated by dexamethasone. In the animal studies, hypertension induced by metopirone was accelerated by salt loading of uni-lateral nephrectomy plus salt loading. In those rats, plasma ACTH, and deoxycorticosterone were markedly increased.
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PMID:Hypertension induced by adrenocortical dysfunction--hypertension in 17 alpha-hydroxylase deficiency and metopirone-induced hypertension. 21 19

1. Pressor responses to angiotensin II, noradrenaline and tyramine were examined in sheep prior to and during the development of corticotrophin-induced hypertension. 2. Pressor responses to angiotensin II amide did not change with corticotrophin (ACTH) administration. Small significant increases in pressor responses to noradrenaline occurred at low doses only (0.27 and 1.06 mumol/h). Significant increases in response to tyramine occurred after 24h of ACTH administration, but were not maintained after 6 days of ACTH. These changes are quantitatively small and do not suggest that changes in pressor sensitivity contribute significantly to the rise in blood pressure following ACTH administration. 3. Sodium depletion significantly reduced the pressor responses to angiotensin II amide at all doses and to tyramine in the middle range only, but did not affect the responses to noradrenaline.
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PMID:The effect of corticotrophin (ACTH) administration on the pressor action of angiotensin II, noradrenaline and tyramine in sheep. 21 61

1. A single intravenous administration of rabbit tonin antiserum into one-kidney one-clip hypertensive rats restored blood pressure to normal in seven out of ten animals. There was little change in blood pressure in two-kidney one-clip hypertensive, uninephrectomized or sham-operated rats. 2. Infusion of tonin in control rats did not modify arterial blood pressure. However, in indomethacin salt-treated rats a marked increase in arterial blood pressure was observed under tonin infusion. 3. Plasma tonin activity was significantly increased in human essential and renovascular hypertension. 4. These findings strongly suggest that tonin is important in the maintenance of high blood pressure. However, other factors (possibly prostaglandins and sodium) have to be modified in order to activate the tonin--angiotensin II system.
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PMID:Tonin--angiotensin II system in hypertension. 21 73

1 Prolonged infusion (11 h) of both saralasin and angiotensin-converting enzyme inhibitor (SQ20881) gradually lowered BP in two-kidney hypertensive rats to levels similar to that in normotensive rats infused with dextrose. 2 Saralasin did not lower BP in DOCA-salt hypertensive rats. 3 These observations support the notion that in chronic renal hypertension, angiotensin II may maintain hypertension by a slowly developing action. 4 Plasma angiotensin II in rats infused with SQ20881 was suppressed relative to renin, but was not eliminated. 5 Chromatography of angiotensin II extracts from dogs infused with converting enzyme inhibitor (SQ14,225) showed that the very high levels of angiotensin I achieved after treatment with SQ14,225 can lead to falsely high estimated angiotensin II levels as a result of angiotensin I cross-reacting with the angiotensin II assay.
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PMID:Inhibitors of the renin-angiotensin system in experimental hypertension, with a note on the measurement of angiotensin I, II and III during infusion of converting-enzyme inhibitor. 22 15

1. Specific angiotensin II (ANGII) receptor binding was measured in regions of the brains of the New Zealand gentically hypertensive and normal rats. 2. ANGII receptor binding was consistently lower in the septum, midbrain, thalamus and posterior medulla of the genetically hypertensive rats than in normal rats. 3. Blood pressure responses to intraventricular injections of ANGII and an ANGII antagonist [Sar1,Ala8]angiotensin were studied in conscious and pentobarbitone-anaesthetized genetically hypertensive and normal rats. In conscious rats no significant difference between the two strains of rat was detected. 4. In pentobarbitone-anaesthetized rats intraventricular injection of 40 microgram of [Sar1,Ala8]angiotensin had a hypotensive effect which was three times greater in the genetically hypertensive rats than that observed in normal rats. The latency of this hypotensive effect was longer than the latency of the hypertensive effect of ANGII. 5. The drinking responses to intraventricular injections of ANGII were similar in genetically hypertensive and normal rats. 6. The physiological role of the ANGII system is discussed and it is concluded that an abnormality of this system in the brain may well be responsible for the hypertension found in the genetically hypertensive rat.
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PMID:Brain angiotensin II binding and central [Sar1,Ala8]angiotensin responses in normal rats and the New Zealand strain of genetically hypertensive rats. 22 96

The purpose of this study was twofold: 1) to determine whether the failure of rats with chronic renovascular hypertension to respond to the angiotensin II antagonist (AIIA) with a decrease in mean blood pressure (BP) was dur to the agonistic effect of the antagonist; and, 2) if this was not the case, to examine whether a positive sodium balance impaired the reversal of the hypertension, after unclamping, in the rats that did not respond to angiotensin inhibitors. For this purpose, rats with chronic, two-kidney Goldblatt hypertension (one renal artery clamped and contralateral untouched) were tested for their BP response to the AIIA (1-Sar-8-Ala-angiotensin II) and to the converting enzyme inhibitor (CEI) SQ20,881, which is devoid of agonistic effect. Approximately 50% of the rats responded to both inhibitors either with no change or with a decrease in BP of less than 20 mm Hg (nonresponders). The other 50% had a decrease in BP of 20 mm Hg or greater (responders). The decrease in BP produced by the AIIA and the CEI correlated significantly (r = 0.76). Nonresponders to both inhibitors were unclamped or sham unclamped. A positive sodium balance was produced before surgery by injecting either 400 or 1000 microEq of sodium and was maintained for 12 hours. Direct BP significantly decreased 12 hours after surgery in the unclamped rats despite a continuous positive sodium balance. In the sham unclamped rats, BP did not change. These data indicate that the failure to respond to the AIIA is not due to the agonistic effect of this peptide. Furthermore, these data suggest that a positive sodium balance is not a major pathogenetic factor in maintaining the high BP in the nonresponder rats, since a positive sodium balance failed to maintain the hypertension after unclamping.
Hypertension
PMID:Angiotensin and sodium balance: their role in chronic two-kidney Goldblatt hypertension. 23 83

Captopril inhibits angiotensin II formation and bradykinin degradation in vivo. Eleven patients with essential hypertension (EH) and four patients with renovascular hypertension (RVH) were treated with captopril for periods ranging from 3 days to 12 months. All patients had a diastolic blood pressure (DBP) over 95 mm Hg after receiving a placebo for 3 days. Captopril given in ascending doses (10-1000 mg/day) caused normalization of blood pressure in all but three patients, one with severe RVH whose pressure fell 11%, one patient with severe EH, whose pressure fell 27%, and one with EH whose blood pressure fell 8.5%. The average control DBP in patients with EH was 113.7 +/- 5.5 (SE) mm Hg and fell to 89.9 +/- 3.6 mm Hg (p less than 0.001), while DBP in patients with RVH fell from 110.7 +/- 7.6 mm Hg to 94.5 +/- 8.2 (p less than 0.005). All patients were studied in balance on a 100 mEq sodium (Na) diet. Plasma renin activity (PRA) versus 24-hour urinary Na excretion increased sevenfold during therapy while converting enzyme activity fell by about one half. The magnitude of the blood pressure response was not related to control PRA. Cardiac output was estimated by echocardiography during placebo administration and during maintenance therapy with captopril. A significant change was not observed. Total peripheral resistance fell an average of 18.9% (p less than 0.05) in 11 of the 13 patients in whom the measurement could be made. It is concluded that captopril effectively lowers blood pressure in patients with EH or RHV by reducing total peripheral resistance.
Hypertension
PMID:Hemodynamic and antihypertensive effects of captopril, an orally active angiotensin converting enzyme inhibitor. 23 84

Sodium depletion was induced in dogs to raise plasma renin activity (PRA) from 1.11 to 26.48 ng/ml/hr. Little overall change in blood pressure (BP) occurred, but cardiac output (CO) and central venous pressure fell, while total peripheral resistance and heart rate (HR) increased. A nonapeptide converting enzyme inhibitor (CEI) produced a fall in BP which was linearly related to log. PRA; the intercept with PRA was at 1.05 ng/ml/hr, close to the average value for dogs on a normal diet. The fall in BP with this agent was not accompanied by an increase in HR or CO. When Sar1-Ala8 angiotensin II was used to antagonize the action of angiotensin, the fall in BP was also linearly related to log. PRA. However, for a given level of PRA this fall in BP was less than that achieved with CEI and the intercept of BP fall with PRA was 2.6 ng/ml/hr. Again with this agent there was little change in HR or CO as BP was reduced. Thus, both antagonists lowered peripheral resistance without exciting the homeostatic reflexes indicating that, as PRA rose above the normal resting level, the angiotensin generated had both a direct and indirect effect in maintaining BP.
Hypertension
PMID:The role of angiotensin in the control of blood pressure during sodium depletion. 23 85


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