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

The dynamic regulation of neurotransmitters and their receptors is an important component of the process of coping and stress adaptation. Among the central neurochemical systems, CRF and the renin-angiotensin may represent major modulatory systems involved in the adaptation of an organism to chronic stress, balancing the response demands that the stressor places on the central nervous system with the potentially detrimental effects that a sustained stress response may produce. As such, the study of these two systems with respect to their neurotransmitters and receptors will allow us to achieve a better perspective on the mechanisms responsible for effective short-term coping with stress as well as long-term adaptation and restoration in response to chronic or repeated stress. It will then be possible to verify the level of activation of different components of the central pathways involved in the mediation of stress responses in rat strains which develop hypertension following chronic exposure to stress. The primary objective of the present paper is to review some facts on the contribution of the central renin-angiotensin system on the regulatory mechanisms involved in the mediation of physiological responses to stress and on the involvement of these neurons in the CNS adaptation in rat strains that are developing hypertension when chronically exposed to stress. Neurons that are expressing angiotensin-receptors may be important in the short-term adaptation to stress by potentiating sympathoadrenal and/or hypophyseo-pituitary-adrenal responses. These same neurons may also participate in long-term stress-adaptation by altering gene expression of their angiotensin receptors. Moreover, these processes represent potential points of dysregulation in the case of extreme, repeated or prolonged stress, and thus in the development of stress-related pathological states such as hypertension and heart diseases.
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PMID:[Relationship between the central renin-angiotensin system, stress and hypertension]. 1048 75

The characteristics of the dialytic population have substantially changed over the past 30 years, becoming older and with a greater number of coexisting diseases. The considerable evolution in treatment modalities has lead to a significant increase in the efficacy and tolerability of dialysis. However, physicians have to deal with illnesses in long term dialysis survivors that may be a consequence of inadequate renal replacement therapy rather than of the dialysis procedure per se. Cardiovascular diseases are the leading cause of death and, although many of the risk factors are the same as in the general population (i.e. hypertension), some appear to be specific to CRF (i.e. hyperparathyroidism, anaemia). Age is the most important demographic factor associated with increased mortality. The increasing incidence of ESRD diabetic patients, as well as malnutrition, also contribute to higher mortality in RRT. The therapeutic answer to a worsening in clinical condition is adequate medical care (starting in the conservative phase), with particular attention being given to correcting anaemia, hypertension, volume overload and hyperparathyroidism, and preventing malnutrition. Treatment modalities also play a crucial role. Data suggest that adequate dialytic dose (and possibly time) can reduce morbidity and mortality, and on-line sodium and potassium modelling can improve intradialytic cardiovascular stability and reduce arrhythmias. Long-term treatment with synthetic high-flux membranes may confer some beneficial effect on beta2-m amyloidosis-related morbidity and may also reduce mortality. Family and social support greatly affect the quality of life of the patients. However technologically advanced, no procedure can succeed unless it is performed in the context of humanised health care directed towards patient needs.
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PMID:Changes in the clinical condition of haemodialysis patients. 1068 6

Secondary hypertension in CRF is characterized by particular features; hemodynamics--abnormal high vascular peripheral resistance relative to the cardiac output level; circadian variability--absence of nocturnal physiological BP decline. Hypertension is the main risk factor for renal disease progression, irrespective of the underlying etiology, and is one of the major determinants of the impressive cardiovascular morbidity and mortality seen in uraemic patients (> 50% cases). The atherosclerotic risk and severe retinopathy are more important in CRF hypertension compared to other causes (including essential HTA) at similar BP levels. Treatment targets for renal patients should be less than 130/90 mmHg. The main treatment modality for ESRD hypertension are sodium and water removal through diet, diuretics and dialytic ultrafiltration. Pro's and con's of antihypertensive medication classes are discussed.
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PMID:[Hypertension in chronic kidney failure (the physiopathology, clinical picture and treatment)]. 1075 68

Hypertension is one of the main risk factors of mortality for children on renal replacement therapy. It has also been recognised as one of the major risk factors for progression of renal failure. The aim of the study was to define the prevalence of hypertension in children with chronic renal failure, treated in a single centre, and to assess the efficacy of its diagnosis and management. Hypertension was present in 27% of 40 children before the onset of chronic renal failure, increasing to 57% with the development of CRF, and reaching 86% at onset of dialysis. Reflux nephropathy, hemolytic-uraemic syndrome and glomerular disease were most frequently associated with severe hypertension. ACE inhibitors (70%), diuretics (52%), and calcium channel blockers were the most frequently used antihypertensives with 49% of the children being on monotherapy. Despite therapy 43% of children had elevated blood pressure levels and 16% had echocardiographic signs of LVH. A 24 hour ambulatory blood pressure measurements were more sensitive in diagnosing hypertension and assessing adequacy of blood pressure control. Early and intensified treatment should prevent end organ damage though optimal blood pressure values to aim obtain are still to be defined.
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PMID:[Hypertension in children with chronic renal failure]. 1089 39

There is an emotional pressor circuit composed of nuclei controlling emotion and stress, which may be the neurophysiological basis for prolonged emotional stress inducing hypertension. The central amygdaloid nucleus (AC) is the most important in this circuit, which widely connects with the other nuclei via its CRF (corticotropin releasing factor)-ergic and SP (substance P)-ergic projection fibers. There is another pressor system composed of the lateral septum (SL), habenula (HB), locus coeruleus (LC), and rostral ventrolateral medulla (RVL); muscarinic receptors are involved in each connection of this system. In view of the facts that the SL also plays an important role in integration of emotion and autonomic reaction, and the AC projects to the SL, it is likely that the SL-acetylcholine (ACh) pressor system is involved in the AC-emotional circuit. The present study demonstrates that injection of receptor blocker into each nucleus in the SL-ACh pressor pathway can reverse the AC pressor response, proving that the SL-HB (and HB-posterior hypothalamus)-LC-RVL pressor system is a component of the AC-emotional pressor circuit.
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PMID:Involvement of rat lateral septum-acetylcholine pressor system in central amygdaloid nucleus-emotional pressor circuit. 1191 90

Sympathetic nervous system (SNS) activity, measured by norepinephrine (NE) turnover rate, was greater in the posterior hypothalamic (PH) nuclei, the paraventricular nuclei (PVN), and the locus coeruleus (LC) of 5/6 nephrectomised (CRF) rats than of control rats. NE secretion from the PH was also greater in CRF than in control rats. These findings demonstrate that SNS activity plays an important role in the genesis of hypertension associated with CRF. The increase in central SNS activity was mitigated by increased local expression of nitric oxide synthase (NOS)-mRNA and nitric oxide (NOx) production. Because angiotensin II may stimulate the central SNS, we tested the hypothesis that losartan, a specific angiotensin II AT(1)-receptor antagonist, may lower blood pressure (BP), at least in part, by central noradrenergic inhibition. To this end, we studied two groups of CRF rats. One group received losartan (10 mg/kg body weight) in drinking water between the 3rd and 4th week after nephrectomy, the second group received drinking water without losartan. SNS activity was measured by NE secretion from the PH using the microdialysis technique. NOS-mRNA gene expression was also measured by RT-PCR in the PH, PVN, and LC of CRF and control rats. Losartan reduced systolic BP from 184+/-3.7 to 152+/-3.1 mmHg and NE secretion from the PH from 340+/-9.7 to 247+/-4.8 pg/ml. CRF rats treated with losartan manifested a significant (p<0.01) increase in the expression of nNOS-mRNA in the PH (from 84+/-1.2 to 99+/-2.6), the PVN (from 44+/-1.5 to 63+/-2.1), and the LC (from 59+/-6.7 to 76+/-2.1). CRF rats also manifested a significant increase (p<0.01) in the expression of IL-1beta the PH (from 41.6+/-2.8 to 54.3+/-1.4), PVN (from 44+/-1.9 to 54+/-1.5), and LC (from 35.5+/-1.6 to 53.5+/-1.9). In conclusion, these studies suggest that the antihypertensive action of losartan in CRF rats may be mediated, at least in part, by inhibition of central SNS outflow. The studies also suggest that the inhibitory action of losartan on the SNS may be mediated by activation of IL-1beta, which, in turn, stimulates nNOS, an important modulator of central SNS activity.
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PMID:Losartan reduces sympathetic nerve outflow from the brain of rats with chronic renal failure. 1196 14

Hypertension and left ventricular hypertrophy (LVH) are commonly associated in patients with CRF starting RDT. We report a case of eccentric LVH with marked dilatation and subsequent mitral incompetence of +3/4 that disappeared after three months of standard hemodialysis. Mrs SN, 62 years old, starting HD, had an echocardiography because of dyspnoea; the echo showed: dilated left atrium (78 ml/m2), moderately dilated left ventricle with normal systolic function (TDV 81 ml/m2, EF 66%), an increased ventricular mass (120 gr/m2) and a high grade mitral incompetence +3/4. After three months standard RDT and a dry weight only 2 kg less, the patients was normotensive without therapy, a cardiac angiogram with a hemodynamic study was performed as a pre-transplant workout: a normal left ventricle was found with normal systolic function (TDV 66, TSV 17, GS 49, EF 75%), and a perfectly competent mitral valve (reflux disappeared). The coronary angiography did not reveal critical stenosis. A new echocardiography confinned the data of the hemodynamic study: hypertensive cardiomiopathy with normal systolic function. After one year the patient has been transplanted, with a good renal function and the cardiac echo unchanged. Relieving uremic toxicity ameliorated the cardiac performance in this particular patient.
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PMID:Eccentric LVH healing after starting renal replacement therapy. 1224 71

The pathophysiology of hypertension in chronic renal failure is complex, but sodium retention and volume expansion play an important role. High salt intake may aggravate hypertension in chronic renal failure, but the mechanisms of this action are not well established. In this study, we have tested the hypothesis that high salt intake aggravates hypertension in rats with chronic renal failure by decreasing nitric oxide synthase (NOS) expression and by increasing sympathetic nervous system activity. Sprague-Dawley rats were subjected to 5/6 nephrectomy (CRF) or sham-operation and fed a regular rat chow. Half of the rats were allowed to drink distilled water and half water containing 1% NaCl. Blood pressure was measured weekly by tail-cuff. Four weeks after nephrectomy or sham-surgery, animals were sacrificed and brains immediately separated and frozen. Norepinephrine (NE) content and NOS-mRNA gene expression were measured in the posterior hypothalamic (PH) nuclei, the locus coeruleus (LC), the paraventricular nuclei (PVN), and in the mesenteric vessels. The endogenous concentration of NE was greater in the PH, LC, and PVN of CRF rats than it was in control animals both during a normal and a high dietary salt intake. In control and CRF rats, the concentration of NE was greater (p < 0.01) during a high than during a normal salt intake in the PH, LC, PVN, and in the mesenteric vessels. A high salt intake reduced the nNOS-mRNA gene expression in the PH (from 100 +/- 2.4 to 46 +/- 1.0;p < 0.01), LC (from 92 +/- 1.9 to 69 +/- 1.2; p < 0.01) and PVN (from 63 +/- 0.8 to 46 +/- 1.3) of CRF rats. A similar reduction occurred in the PH (from 36 +/- 0.8 to 23.6 +/- 1.2), LC (from 33 +/- 1.4 to 24 +/- 1.1) and PVN (from 37 +/- 1. to 27 +/- 1.0) of control rats. High salt intake significantly reduced the nNOS-mRNA gene expression in the mesenteric arteries of control rats, but not in those of CRF rats. In conclusion, these studies provide evidence that in control and CRF rats, high salt intake inhibits nNOS-mRNA expression in the brain, resulting in activation of the sympathetic nervous system and higher blood pressure.
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PMID:High salt intake inhibits nitric oxide synthase expression and aggravates hypertension in rats with chronic renal failure. 1224 72

It has been proved that there are the subfornical organ (SFO)-nucleus paraventricularis (NPV)-rostral ventrolateral medulla (RVL) angiotension II (AngII) pressor system and the central amygdaloid nucleus (AC)-lateral hypothalamus/perifornical region (LH/PF) emotional pressor system in the brain. Because the LH/PF contains abundant AngII ergic neurons projecting to the SFO, the purpose of the present study was to examine whether the (SFO-NPV-RVL) AngII pressor system takes part in the AC-pressor response via AngII ergic neurons in the LH/PF. The results showed that (1) L-glutamate microinjection into the AC or LH/PF induced pressor responses. (2) Both the AC- and LH/PF-pressor responses could be reversed by preinjection of [Sar(1), Thr(8)]-angiotensin II (an antagonist of AngII) into either the SFO, NPV or RVL. Taken together with our previous findings that the projections of the CRF-ergic and SP-ergic neurons in the AC could activate the LH/PF, the above findings prove that: besides several known mechanisms of the brain AngII inducing pressor response, the (SFO-NPV-RVL) AngII pressor system also takes part in the AC-emotional pressor response via AngII ergic projections from the LH/PF to the SFO, which may be the neurophysiological basis of the brain AngII playing an important role in developing hypertension of the SHRs.
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PMID:Subfornical organ-angiotensin II pressor system takes part in pressor response of emotional circuit. 1449 85

Evaluation of anemia: Before beginning epoetin treatment, it is essential to evaluate the level of anemia (Hb < 11-12g/dL) by the following measurements: -Hb concentration -Red blood cell indices (MCV, MCH, MCHC) -Reticulocyte count -Iron stores and availability -C-reactive protein (CRP) Target for anemia treatment: The minimum target Hb concentration to be attained is 11 g/dL. The upper limit is established individually on a clinical basis. Pending further data, it is advisable to maintain and not exceed 12 g/dL for patients with cardiovascular disease, diabetes, and graft access. Use of iron: At the start of epoetin treatment, 150 mg of iron are needed for every expected increase of 1 g/dL of Hb. It is important to achieve and maintain levels of TSAT > 20%, serum ferritin 100 mcg/L and hypochromic red cells > 6% both before initiating epoetin treatment and during its administration. TSAT levels should not persistently exceed > 50% and serum ferritin > 500 mcg/L. When administering oral iron the dose should be at least 200 mg/die elemental iron; on the other hand, when the intravenous route is used, the dose should be 30-60 mg/IV dose in the form of low molecular weight salts (iron sodium gluconate) while the higher doses should be reserved for patients with transferring levels > 170 mg/dL. Administration of epoetin: The dosage of epoetin is individual with more than tenfold variability among individuals and all aiming at the same target Hb concentration. There are no clinical parameters entirely capable of predicting the necessary dosage. Therapeutic range is very wide, without any toxic effects for clinical use up to 100.000 IU/week. The target Hb concentration is reached in most patients with mild anaemia after 2 months' treatment with 4.000-10.000 epoetin (20-50 mcg darbepoetin alpha) per week. The HB concentration, along with the reticulocyte count, must be checked weekly following initiation and monthly during maintenance. Patients with a stable dose-response during conservative therapy may require less frequent monitoring (every 2-3 months). Inadequate response to epoetin treatment If any resistance is encountered, after excluding all the acute and chronic conditions of inadequate response, the reticulocyte count (severe reduction in the presence of anti erythropoietin antibodies) and the erythropoietin dosage should be measured. The target Hb concentration 11-12 g/dL is maintained in 90-95% of the patients by administering 1.000-30.000 IU of epoetin (5-150 mcg darbepoetin alpha) per week in the presence of adequate reserves of iron. Higher dosages define a state of resistance. Diagnosis of pure red cell (PRCA) from anti-erythropoietin antibodies is confirmed by bone marrow examination (almost total loss of erythroblasts). If antierythropoietin antibodies are present or there is a well founded suspicion of PRCA, the administration of epoetin and other similar treatment should be avoided. Side effects of epoetin treatment: The treatment of anaemia with epoetin does not hasten the progression of CRF. Blood pressure is to be checked regularly during initiation of epoetin and the treatment should be discontinued in cases of refractory hypertension or hypertensive encephalopathy. There should be increased surveillance of graft access, especially in those patients who risk vascular depletion. In general, heparin requirements do not increase but it may be advisable to evaluate a dose increase. PRCA from anti-erythropoietin antibodies has been detected with an incidence ranging from 0.12 to 1.1 cases/every 10 thousand patients treated.
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PMID:[Guidelines for the treatment of anemia in chronic renal failure]. 1466 4


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