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

Prolonged stimulation with adrenocorticotropic hormone (ACTH) causes hypertension and increases Na+ intake and urine output in humans and animals. However, its biochemical basis remains to be established. Since renal Na+/H+ exchanger isoforms (NHE) and the sodium pump play an important role in this condition, their levels were examined in rats stimulated with ACTH. Male Wistar rats received daily sc injection of ACTH (30 microg/100 g of body wt) for 4 d. Half of the ACTH-stressed rats were kept for four additional days without injection of ACTH (poststimulation). In a third group, the animals were treated with dexamethasone (50 microg/100 g of body wt) daily for 4 d. A fourth group consisted of unstressed control animals. Levels of NHE proteins were measured by Western blot analysis. Sodium pump activity was assessed by the level of ouabain-sensitive K-stimulated p-nitrophenylphosphatase activity (PNP) in the renal cortex. ACTH caused a selective decrease in NHE-3, but not of NHE-1 or alpha-actin levels. Interestingly, this ACTH-induced change was not duplicated in the animals treated with dexamethasone. Immunofluorescence data demonstrated that NHE-3 is located in the renal proximal tubules. PNP activity, on the contrary, was increased in both the ACTH-stimulated and dexamethasone-treated animals. More important, these changes in NHE-3 and PNP activity returned to the control level poststimulation. In conclusion, while PNP upregulation may be mediated by adrenocortical glucocorticoid, a role for glucocorticoids in the suppression of NHE-3 is less clear. These changes might impair renal tubular Na+ reabsorption and hence increase Na+ and water excretion in ACTH stimulation, thus acting as a counterbalance to normalize blood pressure in ACTH-stimulated animals.
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PMID:Selective suppression of renal Na+/H+ exchanger isoform-3 by prolonged stimulation of rats with adrenocorticotropic hormone. 1195 62

Formerly, the incidence of primary aldosteronism (PA) among patients with hypertension was believed to be less than 1%. However, recent studies have suggested a much higher incidence of 6.59%-14.4% among such patients. These findings suggest that many cases of PA caused by small aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA) have not been properly diagnosed. To make a more accurate diagnosis in such cases, we developed a new diagnostic procedure for localization of PA, namely, adrenal venous sampling under continuous infusion of adrenocorticotropic hormone (ACTH) and administration of angiotensin II receptor blocker (AVS with ACTH and ARB). Here, we confirm the efficacy of this procedure in the case of a 37-year-old male suspected of having PA. The anticipated diagnosis of PA was based on the presence of hypokalemia, low plasma renin activity (PRA), elevated plasma aldosterone concentration (PAC) and left adrenal mass. However, AVS with ACTH and ARB revealed the presence of bilateral multiple adrenal microadenomas. In the new AVS method, neither ACTH nor the renin-angiotensin system (RAS) exert any influence on the plasma aldosterone level, and a more accurate aldosterone secretary state and a more accurate assessment of the aldosterone secretion of both adrenal glands can be recognized than by conventional AVS. Use of this new method should enable identification of additional cases of APA among patients diagnosed with essential hypertension.
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PMID:New diagnostic procedure for primary aldosteronism: adrenal venous sampling under adrenocorticotropic hormone and angiotensin II receptor blocker--application to a case of bilateral multiple adrenal microadenomas. 1204 27

A 67-year-old woman with previously untreated essential thrombocythemia developed bilateral adrenal hemorrhage. She had no known vascular risk factors including smoking, diabetes mellitus, hypertension, and hypercholesterolemia. Her platelet count was 921 x 10(9)/l. She received preemptive steroid therapy to prevent the occurrence of adrenal crisis, but 5 weeks later the replacement therapy was discontinued because the patient fully recovered with a normal adrenocorticotropic hormone stimulation test. Thereafter, she remained well for more than 4 years with a platelet count ranging from 600 to 800 x 10(9)/l. Although adrenal hemorrhage is very rare, it can occur as a hemorrhagic complication of essential thrombocythemia.
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PMID:Bilateral adrenal hemorrhage in essential thrombocythemia. 1210 69

The most potent corticosteroids are 11beta-hydroxylated compounds. In humans, two cytochrome P450 isoenzymes with 11beta-hydroxylase activity, catalyzing the biosynthesis of cortisol and aldosterone, are present in the adrenal cortex. CYP11B1, the gene encoding 11beta-hydroxylase (P450c11), is expressed in high levels in the zona fasciculata and is regulated by adrenocorticotropic hormone (ACTH). CYP11B2, the gene encoding aldosterone synthase (P450c11Aldo), is expressed in the zona glomerulosa under primary control of the renin-angiotensin system. The substrate for P450c11 is 11-deoxycortisol. Mutations in CYP11B1 cause congenital adrenal hyperplasia (CAH) due to 11beta-hydroxylase deficiency. This disorder is characterized by androgen excess and hypertension and is autosomal recessively inherited. Classical and nonclassical forms of 11beta-hydroxylase deficiency can be distinguished. Studies in heterozygotes for classical 11beta-hydroxylase deficiency show inconsistent results with no or only mild hormonal abnormalities (elevated plasma levels of 11-deoxycortisol after ACTH stimulation). Molecular genetic studies of the CYP11B1 gene in 11beta-hydroxylase deficiency have led to the identification of several mutations. Transfection experiments showed loss of enzyme activity in vitro. Molecular genetic studies have practical importance for the prenatal diagnosis of virilizing CAH forms.
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PMID:Congenital adrenal hyperplasia: 11beta-hydroxylase deficiency. 1242 5

The auditory system is permanently open - even during sleep. Its quick and overshooting excitations caused by noise signals are subcortically connected via the amygdala to the hypothalamic-pituitary-adrenal-axis (HPA-axis). Thus noise causes the release of different stress hormones (e.g. corticotropin releasing hormone: CRH; adrenocorticotropic hormone: ACTH) especially in sleeping persons during the vagotropic night/early morning phase. These effects occur below the waking threshold of noise and are mainly without mental control. Animal experiments show noise-induced changes in sensitivity of cellular cortisol receptors by increase of heat-shock proteins, and ultrastructural changes in the tissue of the heart and the adrenal gland. Increased cortisol levels have been found in humans when exposed to aircraft noise or road traffic noise during sleep. The effects of longer-lasting activation of the HPA-axis, especially long term increase of cortisol, are manifold: immuno suppression (e.g. eosinopenia), insulin resistance (e.g. diabetes), cardiovascular diseases (e.g. hypertension and arteriosclerosis), catabolism (e.g. ostoeporosis), intestinal problems (e.g. stress ulcer) etc. Even worse may be the widespread extrahypothalamical effects of CRH/and/or ACTH which have the potential to influence nearly all regulatory systems, causing for example stress-dysmenorrhea etc. as signs of disturbed hormonal balance.
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PMID:Possible health effects of noise induced cortisol increase. 1268 72

Urotensin II is a small peptide whose receptor was recently identified in mammals as the orphan G protein-coupled receptor-14. The reported cardiovascular responses to systemic urotensin II administration are variable, and there is little detailed information on its central cardiovascular actions. We examined the cardiovascular and humoral actions of intracerebroventricular urotensin II (0.02 and 0.2 nmol/kg and vehicle) and intravenous urotensin II (2, 20, and 40 nmol/kg and vehicle) in conscious ewes previously surgically implanted with flow probes and intracerebroventricular guide tubes. Two hours after intracerebroventricular infusion of urotensin II (0.2 nmol/kg over 1 hour; n=5), heart rate (+56+/-13 beats per minute [bpm]), dF/dt (an index of cardiac contractility; +533+/-128 L x min(-1) x s(-1)), and cardiac output (+3.4+/-0.4 L/min) increased significantly compared with vehicle, as did renal, mesenteric, and iliac blood flows and conductances. Plasma epinephrine, adrenocorticotropic hormone, and glucose levels also increased dramatically (+753+/-166 pg/mL, +14.3+/-3.5 pmol/L, and +7.0+/-1.4 mmol/L, respectively). All of these variables remained elevated for up to 4 hours after infusion. In contrast, 1 hour after intravenous urotensin II (40 nmol/kg bolus; n=6), a sustained tachycardia (+25+/-8 bpm) ensued, but cardiac output, cardiac contractility, total peripheral conductance, and plasma glucose levels did not change significantly. In summary, this is the first study to show that urotensin II acts centrally to stimulate sympathoadrenal and pituitary-adrenal pathways, resulting in increased adrenocorticotropic hormone and epinephrine release and potent chronotropic and inotropic actions. In contrast, tachycardia was the only major response to intravenous urotensin II. These findings suggest that urotensin II is a novel stimulator of central pathways that mediate responses to alerting stimuli or stress.
Hypertension 2003 Sep
PMID:Urotensin II acts centrally to increase epinephrine and ACTH release and cause potent inotropic and chronotropic actions. 1288 91

A 61-year-old woman was admitted to our hospital with hypertension and diabetes mellitus, and was found to have Cushing's syndrome. Radiological and endocrinological findings suggested adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. Simultaneous bilateral laparoscopic adrenalectomy was performed, minimizing the number of trocar sites and operation time. Success was attributed to the careful selection of trocar sites to permit safe dissection.
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PMID:Adrenocorticotropin-independent macronodular adrenal hyperplasia treated by simultaneous bilateral laparoscopic adrenalectomy. 1288 68

Glucocorticoid overexposure in utero may underlie the association between low birth weight and subsequent development of common cardiovascular and metabolic pathologies. Previously, we have shown that prenatal dexamethasone (DEX) exposure in rat reduces birth weight and programs the hypothalamic-pituitary axis and fasting and postprandial hyperglycemia in adult males and hypertension in adult males and females. This study aimed to determine 1) whether there were gender differences in prenatal DEX-programmed offspring, and 2) whether the renin-angiotensin system (RAS) plays a role in the programming of hypertension. Rats exposed to DEX in utero (100 microg.kg(-1).day(-1) from embryonic days 14-21) were of lower birth weight (by 12%, P < 0.01) and displayed full catch-up growth within the first month of postnatal life. DEX-treated male offspring in adulthood selectively displayed elevated plasma adrenocorticotropic hormone (by 221%) and corticosterone (by 188%, P < 0.05), postprandial insulin-glucose ratios (by 100%, P < 0.05), and hepatic expression of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (by 38%, P < 0.05). Conversely, DEX-programmed females were hypertensive (by 11%, P < 0.05), with elevated hepatic angiotensinogen mRNA expression (by 9%, P < 0.05), plasma angiotensinogen (by 61%, P < 0.05), and renin activity (by 88%, P < 0.05). These findings demonstrate that prenatal glucocorticoids program adulthood cardiovascular and metabolic physiology in a gender-specific pattern, and that an activated RAS may in part underlie the hypertension associated with prenatal DEX programming.
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PMID:Glucocorticoid exposure in late gestation in the rat permanently programs gender-specific differences in adult cardiovascular and metabolic physiology. 1523 53

A pathogenetic role of the renin-angiotensin-aldosterone system has been implicated in cats in both systemic arterial hypertension and hypokalemic myopathy. Yet, measurement of plasma aldosterone concentrations (PACs) and plasma renin activity (PRA) has not unequivocally pointed to hyperaldosteronism as a cause of these conditions. To obtain appropriate reference ranges, this study included a large number (130) of healthy house cats of different breeds without a history of recent illness and plasma concentrations of urea and creatinine below the upper limit of the respective reference ranges. In addition, the pituitary-adrenocortical axis was studied by measuring plasma concentrations of adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), and cortisol. Reference ranges for PACs (110-540 pmol/L; 40-195 pg/mL), PRA (60-630 fmol/L/s; 0.3-3 ng/mL/h), and the aldosterone to renin ratio (ARR) (0.3-3.8) were very similar to those established in the same laboratory for humans in a supine position. No breed differences were found. The ARRs in neutered cats were significantly higher than in intact cats, primarily because of low PRA in neutered cats. The ARRs of cats > or = 5 years of age were significantly higher than those of cats < 5 years of age. The plasma concentrations of ACTH, alpha-MSH, and cortisol did not correlate significantly with PAC. Thus, although blood sampling was performed in cats in nonstandardized positions and was associated with a wide variation of stress responses, the references ranges of PAC, PRA, and ARR were similar to the relatively narrow limits established for humans under standardized conditions. The effects of neutering and aging on PRA and ARR warrant further investigation.
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PMID:Plasma renin activity and plasma concentrations of aldosterone, cortisol, adrenocorticotropic hormone, and alpha-melanocyte-stimulating hormone in healthy cats. 1551 76

Peripheral and brain angiotensin II AT(1) receptor blockade decreases high blood pressure, stress, and neuronal injury. To clarify the effects of long-term brain Ang II receptor blockade, the AT(1) blocker, candesartan, was orally administered to spontaneously hypertensive rats (SHRs) for 40 days, followed by intraventricular injection of 25 ng of Ang II. Before Ang II injection, AT(1) receptor blockade normalized blood pressure and decreased plasma adrenocorticotropic hormone (ACTH) and corticosterone. After central administration of excess Ang II, the reduction of ACTH and corticosterone release induced by AT(1) receptor blockade no longer occurred. Central Ang II administration to vehicle-treated SHRs further increased blood pressure, provoked drinking, increased tyrosine hydroxylase (TH) mRNA expression in the locus coeruleus, and stimulated sympathoadrenal catecholamine release. Pretreatment with the AT(1) receptor antagonist eliminated Ang II-induced increases in blood pressure, water intake, and sympathoadrenal catecholamine release; inhibited peripheral and brain AT(1) receptors; increased AT(2) receptor binding in the locus coeruleus, inferior olive, and adrenal cortex; and decreased AT(2) receptor binding in the adrenal medulla. Inhibition of brain AT(1) receptors correlated with decreased TH transcription in the locus coeruleus, indicating a decreased central sympathetic drive. This, and the diminished adrenomedullary AT(1) and AT(2) receptor stimulation, result in decreased sympathoadrenomedullary stimulation. Oral administration of AT(1) antagonists can effectively block central actions of Ang II, regulating blood pressure and reaction to stress, and selectively and differentially modulating sympathoadrenal response and the hypothalamic-pituitary-adrenal stimulation produced by brain Ang II--effects of potential therapeutic importance.
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PMID:Oral administration of an AT1 receptor antagonist prevents the central effects of angiotensin II in spontaneously hypertensive rats. 1551 36


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