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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 9 (1982), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Angiotensin II (ANG II) may increase blood pressure by central nervous system mechanisms. The involvement of the sympathetic nervous system in the centrally-induced pressor effect of ANG II in the rat was investigated.2 Plasma noradrenaline concentrations, measured as an index of sympathetic nervous system activity, increased after intracerebroventricular (i.e.v.) injection of pressor doses of ANG II, both in normotensive and in spontaneously hypertensive rats.3 To assess the functional significance of this, the sympathetic nervous system was inhibited by phentolamine, reserpine, and guanethidine. In phentolamine-infused rats, low doses of i.c.v. ANG II elicited a blood pressure decrease, but at maximal pressor doses, no difference between phentolamine-treated and control rats was observed. In reserpinized rats, the central pressor effect of ANG II was greater than in controls. Guanethidine pretreatment did not affect the blood pressure response to i.c.v. injected ANG II.4 It is concluded that the central pressor effects o f ANG II are accompanied by a stimulation of the sympathetic nervous system. In the rat, this stimulation may be functionally important for the initial phase of the central pressor action. This could not be established for the maximal pressor responses.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 205 (1994), S. 552-557 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0888-7543
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1440
    Keywords: Hyponatremia ; Vasopressin ; Thirst ; Diuretics ; Cardiac failure ; Cirrhosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Because hyponatremia is frequently associated with preceding diuretic treatment and unrestricted fluid indake — conditions which have not been addressed sufficiently in published literature — we studied the pathophysiology and the clinical setting of such hyponatremia in a large group of internal medicine patients. We observed: a) Of an initial 310 patients with chemical hyponatremia only 204 (64%) had an associated plasma hypoosmolality. Sience a normal plasma osmolality excludes a disturbance of water metabolism only the 204 patients with hypoosmolar hyponatremia were included in the study. This data shows that plasma osmolality is an essential measurement in any evaluation of hyponatremia. b) In 204 consecutive patients with hypoosmolar hyponatremia the electrolyte disturbance was related to advanced congestive cardiac failure in 25%, decompensated liver cirrhosis in 18%, volume contraction in 28%, syndrome of inappropriate antidiuretic hormone secretion in 19% and renal insufficiency in 4%. c) Plasma vasopressin was measurable in 90% of the 204 patients. It is known that radioimmunoassays to measure vasopressin fail to reliably detect low concentrations of circulating vasopressin (〈0.5 pg/ml). It may therefore be stated that hypoosmolar hyponatremia was generally characterized by a failure of antidiuretic hormone suppression. d) Mean daily fluid intake of hyponatremic patients was 2.35±0.15 l. In the presence of stimulated vasiopressin this large a fluid intake is bound to worsen the severity of hyponatremia. e) Of 204 patients 126 were treated with diuretics at the time of study. In these patients hyponatremia worsened during such treatments and was associated with evidence of prerenal azotemia. However there were no significant differences between diuretic-treated and -untreated patients with respect to plasma vasopressin stimulation and amount of fluid intake. In conclusion, stimulated vasopressin and high fluid intake explain the hyponatremia observed in the present study. This applied similary to diuretictreated and -untreated patients.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 68 (1990), S. 1127-1133 
    ISSN: 1432-1440
    Keywords: Thirst regulation ; Vasopressin ; Renin-angiotensin-system ; Atrial natriuretic peptide ; Endstage renal disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary About 30% of hemodialyzed patients are suffering from chronic fluid overload despite advice to restrict the oral fluid intake. To investigate the cause of the abnormal drinking behaviour a clinical study was performed in 51 non-diabetic patients with endstage renal disease exhibiting lower interdialytic weight gain (〈3 kg,n=17) and increased interdialytic weight gain (〉3 kg,n=34). Blood pressure, body weight self-estimated thirst intensity before and after hemodialysis were analyzed. Biochemical and behavioral variables were measured including hormonal factors of water and sodium metabolism. Significant differences of dry weight, creatinine, urea nitrogen and thirst intensity were found between the two groups. Catecholamines, renin, angiotensin II, aldosterone, vasopressin and atrial natriuretic peptide exhibited a similar pattern in both groups. Atrial natriuretic peptide decreased during hemodialysis in both groups, angiotensin II, however, and norepinephrine showed an exaggerated response to ultrafiltration rate in polydipsic patients. These results suggest that changes in serum osmolality during hemodialysis did not contribute to thirst and drinking behaviour. It seems that postdialytic hypovolaemia together with higher plasma-angiotensin II-levels is responsible for increased oral intake of fluid and excessive weight gain.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1440
    Keywords: Somatostatin ; Glomerular filtration rate ; Vasoactive hormones ; Renal sodium excretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The acute effects of i.v. somatostatin (250 mcg bolus followed by 250 mcg/h continuous infusion for two hours) on renal hemodynamics, renal electrolyte and water handling, and urinary excretion of catecholamines and prostaglandins, as well as on plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, dopamine, glucagon, and plasma renin activity were studied in seven normal subjects. Somatostatin decreased effective renal plasma flow and glomerular filtration rate, osmotic and free water clearances, urine volume, and sodium and potassium excretion, while urinary osmolality, fractional excretion of sodium, and phosphate excretion increased significantly. Plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, and dopamine remained unchanged, while plasma renin activity (3.0±0.25 vs 2.4±0.2 ng AngI/ml/h;p}〈0.01) and glucagon levels (40±11 vs 20±16 pg/ml;p}〈0.01) decreased. Urinary excretion of norepinephrine, epinephrine, dopamine, PGE2, and PGF2alpha was suppressed under somatostatin. A significant positive correlation was found between urinary dopamine and sodium excretion (r=0.7;p}〈0.001) and urinary postaglandin E2 and glomerular filtration (r=0.52;p}〈0.01). Without accompanying changes in plasma osmolality and vasopressin concentration significant antidiuresis occurred, suggesting a direct tubular effect of somatostatin. However, the hormone-induced changes are due mainly to the decrease in renal plasma flow. The results demonstrate that somatostatin at supraphysiological doses exerts significant effects on the kidney.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 63 (1985), S. 989-999 
    ISSN: 1432-1440
    Keywords: Dehydration ; Hemodynamics ; Hypertension ; Vasopressin ; Vasopressin antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The two major biological actions of vasopressin are antidiuresis and vasoconstriction. The antidiuretic action of low concentrations of vasopressin is well established and concentrations 10 to 100 times above those required for antidiuresis elevate arterial blood pressure. Antidiuresis is mediated by V2-receptors at the kidney, whereas vasopressin constricts arterioles by binding at V1-receptors. Pharmacological effects of specific antagonists of the vasoconstrictor activity of vasopressin (vascular or V1-receptor antagonists) are presented. Low concentrations of vasopressin do have significant hemodynamic effects. Physiological concentrations of vasopressin cause vasoconstriction and elevate systemic vascular resistance. In subjects with intact cardiovascular reflex activity, however, cardiac output falls concomitantly and blood pressure therefore does not change. In animals with baroreceptor deafferentation or in patients with blunted baroreceptor reflexes (autonomic insufficiency) a rise in plasma vasopressin causes vasoconstriction and an increase in blood pressure, because cardiac output does not fall under these conditions. Vasopressin contributes substantially via increase in systemic vascular resistance to maintain blood pressure during water deprivation. During hemorrhage and hypotension vasopressin has a major role to restore blood pressure. In experimental hypertension vasopressin contributes to the development and maintenance of high blood pressure in DOCA, but not in genetic hypertensive rats. The role of vasopressin in human hypertension is not yet clear. Vasopressin in extrahypothalamic areas of the brain affects circulatory regulation by interaction with central cardiovascular control centers. The exact mechanism of how vasopressin is involved in central regulation of blood pressure remains to be established. In contrast to our previous opinion vasopressin is a vasoactive hormone also at low plasma concentrations. Its cardiovascular action is more complex than previously assumed.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0090-6980
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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