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

Changes in plasma ADH levels and plasma aldosterone levels (PA) were studied in patients with end-stage renal disease (N = 40). The patients were divided into two groups according to their plasma renin activity (PRA) into a low renin (LR, n = 9) and a high renin group (HR, n = 31). The metabolic clearance rate (MCR) of plasma ADH was also investigated in 4 patients and 5 normal volunteers. Additionally, it was examined whether plasma ADH, aldosterone and renin were permeable through the dialysis membrane. Pre- and post-dialysis plasma ADH levels in LR were similar to those in the HR group. However, pre- and post-dialysis PA in the HR group were significantly greater than those in the LR group. Post-dialysis PRA was significantly increased in HR compared to pre-dialysis, but not in LR. Pre- and post-dialysis plasma osmolality was increased in both groups, but effective plasma osmolality (EPosm) was within the normal range. There was a significant correlation between EPosm and plasma ADH level both before and after haemodialysis, but the majority of the abnormally high values of ADH compared to the normal values was found within the normal range of EPosm. The patients exhibited high blood pressure and a rise in body weight, and haemodialysis caused a significant fall in body weight and blood pressure in both groups. MCR of ADH was significantly lower in the patients than that in normal subjects. Plasma ADH proved to be permeable through the dialysis membrane in all cases, but aldosterone in only a few cases. Renin was not permeable.
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PMID:Effect of haemodialysis on plasma ADH levels, plasma renin activity and plasma aldosterone levels in patients with end-stage renal disease. 390 90

The aging kidney suffers reduction both in mass and in glomerular filtration rate. These changes may be totally or partially due to atherosclerosis and hypertension, which reduce renal blood flow. Superimposed on these processes, and perhaps responsible for primary loss of renal mass irrespective of renal vascular disease, is glomerular damage and involution that is a consequence of adaptive increases in glomerular perfusion pressure that occurs as the number of nephrons decline with age. The data available at this time do not allow us to distinguish between these two potential mechanisms of renal senescence. The decline in GFR is in turn responsible for reduced renal acidification and the reduced renal clearance of drugs that are normally removed by the kidney. Certain renal functions, however, are depressed to a greater extent than is GFR. Both the ability to maximally dilute the urine and to maximally concentrate it are controlled by serum ADH concentrations and by the action of that hormone on the collecting duct. Aged rats do not maximally secrete ADH under conditions of dehydration and the effect of ADH on the kidney is also attenuated. Elderly humans also cannot maximally suppress ADH secretion when serum osmolality is reduced. Likewise, the renin-angiotensin-aldosterone axis is poorly responsive to volume depletion in aging subjects. As a result, elderly individuals cannot maximally retain sodium under conditions of plasma volume contraction out of proportion to reduction in GFR. The kidney is the site of vitamin D1 hydroxylation. Hydroxylation of vitamin D is reduced out of proportion to any reduction in GFR in the rat. There are no data as yet available on the effect of aging and the production of erythropoietin, a principal regulator of red blood cell mass. Neither are there data available on changes that might occur with advancing age in the ability of the aging kidney to metabolize various hormones, such as parathyroid hormone, glucagon, and insulin. The mechanisms and the full biochemical and physiologic consequences of renal senescence remain to be fully elucidated.
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PMID:The aging kidney. 391

The renal handling of water by SBH and SBN rats was evaluated under basal conditions and following various intervention procedures. During 17 weeks of unrestricted water intake, SBH rats drank less water and excreted less urine with a higher osmolality than SBN. The differences in urine volume and osmolality persisted during 2 weeks of paired water intake. Acute water loading elicited comparable dilution of the urine in the two strains. Water deprivation for 48 h resulted in a marked rise in urine osmolality, which tended to be higher in SBN. Administration of exogenous vasopressin in water loaded animals caused a similar rise in urine osmolality. Papillary solute and urea content was higher in SBH than in SBN, but comparable in water loaded animals. The results show that although SBH differ from SBN rats in the handling of water under basal conditions, their renal diluting and concentrating capacity is comparable at extreme conditions. GFR and RBF were equal in both strains. The data suggest that SBH rats have increased renal water reabsorption as compared to SBN, which may be mediated by ADH, PG or other mechanisms. This characteristic may be related to their propensity to develop hypertension.
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PMID:Water handling by the sabra hypertension prone (SBH) and resistant (SBN) rats. 401

We have previously suggested that inhibition of renin release by sodium chloride is related to absorptive chloride transport in the loop of Henle. Infusion of sodium chloride fails to inhibit renin release in the adrenalectomized (Adx) rat, and dexamethasone restores renin responsiveness to sodium chloride. The purpose of the present study was to evaluate the relationship between loop function (urinary diluting and concentration capacity) and plasma renin concentration (PRC) in the Adx rat. After hypotonic sodium chloride infusion, free water clearance (CH2O) of Adx rats (0.56 ml/hr/100 g +/- 0.17 SE) was decreased (p less than 0.01) compared to controls (2.86 ml/hr/100 g +/- 0.29 SE); PRC of Adx rats (61.9 units/ml +/- 11.2 SE) was increased (p less than 0.01) above controls (6.0 units/ml +/- 1.7 SE). These differences persisted after administration of d(CH2)5Tyr(Et)VAVP, a potent ADH antagonist. In separate groups of animals, after water deprivation, urine concentration of Adx rat (1,401 mOsm/kg +/- 45 SE) was less (p less than 0.01) than that of controls (2,117 mOsm/kg +/- 169 SE). Dexamethasone normalized both CH2O and urinary concentrating ability and also decreased PRC in Adx rats. Thus, in the glucocorticoid deficient rat, increased renin release is associated with impaired loop function. The loop defect may account for high PRC that is not suppressed by sodium chloride.
Hypertension
PMID:Mechanism of increased renin release in the adrenalectomized rat. Adrenal insufficiency and renin. 633 60

The authors have studied on 25 cases of hypercorticism, one of the mechanisms of producing arterial hypertension, the renin-angiotensin system. The study showed that in only 20% of the cases plasma renin activity was high whereas in the remaining 80% other mechanisms were responsible for the hypertension. In the cases in which the plasma activity of renin was high, by studying the changes in the value of electrolytes we were able to derive some understanding of the mechanism of action of the RA2A system. Thus, the literature data show that sometimes the excess of glucocorticoids causes hypertension by activating directly the RA2A system and concomitently inhibiting the renin-kalikrein system (RKKS) and PgS; at other times, the excess of glucocorticoids is exerted on the same renin-angiotensin system, but via ACTH and ADH, the electrolytes values being those that demonstrate the borrowed mechanism.
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PMID:The role of the renin-angiotensin system in arterial hypertension in hypercorticism. 634 18

The effects of sodium, sympathetic innervation, and central adrenergic structures on the development of changes in renal vascular reactivity were studied in unilaterally nephrectomized rats treated with a single implant of deoxycorticosterone acetate (DOCA; 100 mg/kg). Vascular reactivity to norepinephrine (NE) and vasopressin (ADH) was assessed in isolated kidneys perfused with a synthetic medium. Influence of sodium was determined by placing DOCA-treated rats on high, normal, and low sodium intakes. Neural influence was studied by means of local denervation of the renal artery and by intravenous (iv) and intraventricular (ivt) administration of 6-hydroxydopamine (6-OHDA). Marked changes in renal vascular reactivity in DOCA-treated rats were already apparent prior to the rise in blood pressure. Dose-response curves for NE and ADH showed parallel leftward shifts and decreased threshold doses. Normal sodium intake, local denervation, and peripheral sympathectomy had no effect on the development of these vascular changes in DOCA-treated rats. However, sodium deficiency and ivt administration of 6-OHDA totally prevented development of enhanced vascular reactivity. These results imply that increased vascular reactivity is a major factor in the development of DOCA-hypertension.
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PMID:Significance of sodium, sympathetic innervation, and central adrenergic structures on renal vascular responsiveness in DOCA-treated rats. 741 27

A 13-year-old girl with multiple minor anomalies and severe mental retardation had recurrent episodes of severe vomiting. At each episode, marked elevations of plasma ADH, ACTH, cortisol and salivary type amylase were found with reduction of serum Na level and osmolarity. This case is similar to that with periodic ACTH-ADH discharge syndrome (Sato). However, she had underlying disease, and neither hypertension nor depressive state was observed. Latent SIADH was detected by water loading test. After DZP administration, ADH secretion was suppressed in this test, and actually the duration of each attack was shortened. We considered that her vomiting was closely related with hypothalamic dysfunction, especially latent SIADH.
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PMID:[Congenital multiple anomaly syndrome with recurrent vomiting accompanied with latent SIADH; a case report]. 828 Apr 47

A 62-year-old male with small cell lung cancer (SCLC) associated with Cushing's syndrome and diabetes insipidus (DI) is reported. The patient was referred to our hospital for treatment of SCLC. A diagnosis of paraneoplastic Cushing's syndrome was made on the basis of an elevated serum ACTH (623.5 pg/ml) level, elevated excretion of urinary 17-OHCS (18.01 mg/day), obesity, hypertension, hyperglycemia, persistent hypokalemia, alkalosis, and no history of diabetes mellitus. He was also diagnosed as having DI based on polyuria and polydipsia, low specific gravity of the urine (1.007-1.010), low serum ADH (1.4 pg/ml) level, normal plasma osmolarity (29 mOsm/kg H2O), and the results of water deprivation test. DI and a left visual field defect was suggestive of metastasis to the pituitary region, but no lesion was detected by either CT scan or MRI scan. The patient failed to show a good response to intensive chemotherapy, and died of the tumor five months after commencing chemotherapy. Post-mortem examination revealed metastases to the hypothalamic-neurohypophyseal region, lungs, liver, adrenal glands, bone, bone marrow, and hilar and mediastinal lymph nodes.
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PMID:[A case of small cell lung cancer associated with diabetes insipidus and Cushing's syndrome]. 839 May 89

In this prospective, randomized study, two regimens of total intravenous anaesthesia (TIVA), with propofol and S(+)-ketamine (S-ketamine) and with propofol and alfentanil, were compared with reference to endocrine stress response, circulatory effects and recovery. METHODS. The investigation was conducted in two groups of 20 ASA I-III patients over 60 years of age who were scheduled for endoprothetic orthopaedic surgery. After oral premedication with midazolam, patients received a TIVA with body-weight-adjusted doses of propofol, and S-ketamine or alfentanil as the analgesic component. For CPPV (PEEP 5 mbar), air and oxygen (FiO2 33%) were used. For muscle relaxation, patients of both groups received vecuronium in body-weight-adjusted doses. Blood samples were taken through a central venous line at seven time points before induction of anaesthesia and on the first morning after the operation also for analysis of epinephrine, norepinephrine (by HPLC/ECD), and ADH, ACTH and cortisol (by RIA). In addition, SAP, HR, arterial oxygen saturation, recovery from anaesthesia and side effects were observed. RESULTS. The two groups had comparable group mean values for age (S-ketamine group 71 years, alfentanil-group 70 years), other biometric data, and duration of anaesthesia and operation (Table 1). Plasma levels of epinephrine, norepinephrine (Table 2, Fig. 1), ADH (Table 2, Fig. 2) ACTH and cortisol (Table 2, Fig. 3) were higher in the S-ketamine-group (P < 0.05) owing to the intraoperative course of these endocrine parameters. Before induction, and on the first morning after the operation, levels were comparable between the groups. 5 min after the induction of anaesthesia, SAP and HR (Table 3) were significantly lower in the alfentanilgroup (P = 0.001). Recovery from anaesthesia (orientation with respect to person and location) was faster in the alfentanilgroup (16 vs 39 min, P = 0.001). An arterial oxygen saturation below 90% was observed in 7 patients in the S-ketamine- and 13 patients in the alfentanilgroup (P = 0.03). Four patients with S-ketamine reported dreams, and 1 dream was judged negative. Postoperative emesis was found in 6 patients in the S-ketaminegroup and 12 patients in the alfentanilgroup (P = 0.03). All patients said they would agree to undergo the same anaesthetic technique again. CONCLUSIONS. Considerable differences were found in the endocrine stress response of the two groups. With respect to endocrine response and circulation, TIVA with propofol and S-ketamine had sympathomimetic properties with positive circulatory effects and led to moderate endocrine stimulation. This should be kept in mind in patients with hypotension, hypothyrosis, or adrenocortical insufficiency; because "eustress" might be beneficial in this group of patients. On the other hand, TIVA with propofol and alfentanil showed sympatholytic properties, with negative circulatory effects and a remarkable reduction of endocrine stress response. This might be beneficial in patients with hypertension and states of endocrine hyperfunction. Both regimens were accompanied by such typical side effects as dreams, delayed recovery, reduced ventilation, and emesis, which should also be considered.
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PMID:[Total intravenous anesthesia (TIVA) in geriatric surgery. S-(+)-ketamine versus alfentanil]. 859 65

Creatinine clearance decreases with age by 1 ml/min/year after 40 years of age, although serum creatinine remains constant because of reduction of muscle mass. Reduction of water intake may occur in the elderly because of a reduced sensation of thirst; this is associated with a tendency to lose water with urine. The capacity to respond to sodium load is impaired in aged kidneys, thereby leading to ECV expansion and hypertension. But there is also, in the elderly, a reduced capacity for retaining sodium (FENa is higher than in young subjects), making old subjects sensitive to salt depletion and ECV contraction. Hypernatraemia (Nas > 150 mmol/l) is not infrequent in the elderly (1%) and is usually due to water deficiency (old subjects should be forced to drink), and rarely to iatrogenic excess of sodium. It is the abrupt occurrence of severe hypernatraemia that causes neurological symptoms due to dehydration and brain shrinking, which may lead to cerebral haemorrhage and death. Hyponatraemia (Nas < 130 mmol/l) is frequent among the elderly (7-11%) and is mainly due to water overload, which is usually iatrogenic. Hypovolaemic hyponatraemia occurs when salt depletion causes ECV contraction > 10%, and is due to water retention in an attempt to normalize ECV. Hypervolaemic hyponatraemia is due to ADH hypersecretion because of a decrease in 'effective' circulating blood volume. 'Pseudohyponatraemia' may occur because of hyperlipidaemia or hyperproteinaemia. It is the abrupt occurrence of severe hyponatraemia that causes neurological symptoms (water intoxication), secondary to the oedomatous swelling of the brain within the skull. While rapidly occurring hyponatraemia may be lethal, slowly occurring hyponatraemia is usually asymptomatic. Rapid correction of hyponatraemia may cause cerebral dehydration and 'osmotic demyelination syndrome' ('central pontine myelinosis'). Decrease (e.g. by diuretics) or increase (e.g. by ACE-inhibitors, non-steroidal anti-inflammatory drugs, beta-blockers) or serum potassium may occur in the elderly. Diuretics should be used with caution in elderly subjects to avoid salt depletion, hypotension and renal function impairment.
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PMID:Some sodium, potassium and water changes in the elderly and their treatment. 905 29


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