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

Maintenance of normotension rests upon the overall salt and water balance, which, in the event of disequilibrium, modifies body fluid, cardiac output and total peripheral resistance. The kidneys play a central role in this hydro-saline regulation. The central and autonomous nervous systems, the renin-angiotensin system, the mineralocorticoids, the antidiuretic hormone and the kallikrein-bradykinin-prostaglandin system all affect this regulation and are closely interrelated. The role of each of these nervous and endocrine systems in hypertension, and their close interrelationship, is briefly reviewed.
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PMID:[Physiopathology of arterial hypertension. Role of the nervous system and of the hormones]. 101

The vasopressor response to angiotensin II was found useful in the differential diagnosis of arterial hypertension and for a better understanding of its pathogenesis. Sodium supply was proved to influence significantly the pressor response to angiotensin II and not that to noradrenaline thus implying the presence of arterial receptors which bind angiotensin specifically. Angiotensin caused an increase of the urinary excretion of electrolytes in hypertensive patients and a decreased electrolyte excretion in normotensives. In most hypertensive patients angiotensin was found to decrease the plasma angiotensinogen and to activate the bradykinin-bradykininogen and fibrinolytic systems. In the presence of urinary infection angiotensin increased the platelet adhesiveness and the thrombelastographic changes proved that in this condition angiotensin increases the tendency to thrombosis.
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PMID:Angiotensin II. Vascular reactivity and humoral effects. 102 54

The state of the kinin system of blood was studied in terms of its content of kininogen, prekallikrein, kallikrein inhibitor and the spontaneous esterase activity. The examination was conducted in 10 normal individuals and in 81 hypertensive patients with labile and stable arterial pressure and an uncomplicated course. The studies were conducted at rest, during the transfer into an orthostatic position, and after 15 or 60 minutes of walking. The normals demonstrated an activation of the kinin system that ensued in orthostasis, but was more distinct at walking. A significant correlation was noted between the content of prekallikrein and kininogen in all the states under examination. In cases of labile arterial hypertension an increased activation of the blood kinin system was observed at rest, a lack of its activation at walking, and disorders in the correlation between the content of prekallikrein and kininogen. The observed changes in the kinin system may affect the central haemodynamics and the formation of the hyperkinetic type of circulation.
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PMID:[Characteristics of changes in the kinin system of blood in hypertensive disease]. 108 40

Deoxycorticosterone acetate (DOCA)-salt hypertension was induced in Brown Norway (BN) kininogen-deficient rats (BN-Ka) and normal rats from the same strain (BN-Ki) after nephrectomy. Systolic blood pressure, which was determined by the tail-cuff method, of BN-Ki increased gradually during this treatment. In contrast, the blood pressure of mutant BN-Ka increased rapidly 2 weeks after the onset of the treatment. Urinary excretion of active kallikrein and prokallikrein increased at the same degree in rats of both strains during this treatment. Significant increase in urinary sodium excretion was observed with a tendency to increase in urine volume during the treatment in normal BN-Ki rats, whereas both parameters were essentially not increased in mutant BN-Ka rats, which could not generate urinary kinin. Aprotinin infusion by osmotic minipump to normal BN-Ki rats during the DOCA-salt treatment resulted in significant further increase in the systolic blood pressure.
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PMID:Essential role of kallikrein-kinin system in suppression of blood pressure rise during the developmental stage of hypertension induced by deoxycorticosterone acetate-salt in rats. 128 79

We determined kinin-generating activity (kininogenase) in the thoracic aorta of spontaneously hypertensive rats (SHRs) at age 5 and 15 weeks and in appropriately age-matched Wistar-Kyoto (WKY) rats. Aorta homogenates were incubated with partially purified dog kininogen, and the resulting kinins were extracted with ethanol. The kinins were determined by a sensitive kinin radioimmunoassay (RIA). Kininogenase activity was expressed as mean +/- SEM, picogram kinin generated/mg x protein/h. Active kininogenase in SHR was approximately one-third in 5-week-old and about one-fifth in 15-week-old rats when compared with their normotensive controls. Total kininogenase activity in SHRs was approximately 80% and 58% of the normotensive controls at ages 5 weeks and 15 weeks, respectively. Active enzyme was 14% of the total in 5-week-old SHRs, and it was only 5% of the total in 15-week-old SHRs. It seems unlikely that the changes in kininogenase are secondary to hypertension because blood pressor is only marginally elevated at 5 weeks according to the literature. We hypothesize that genetic hypertensive rats may suffer from an inherent deficiency in the kininogenase activity of the vascular wall. The deficiency may also be in the mechanism of activation of precursor enzyme.
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PMID:Kininogenase of the aortic wall in spontaneously hypertensive rats. 128 21

We investigated the chronic effect of bradykinin B2-receptor blockade on the antihypertensive actions of the angiotensin-converting enzyme (ACE) inhibitor ramipril in three different hypertensive rat models, the two-kidney/one-clip (2K1C) hypertensive Wistar rat, the kinin-deficient 2K1C hypertensive Brown Norway Katholieke (BN-K) rat, and the spontaneously hypertensive rat (SHR). Chronic blockade of bradykinin B2 receptors by subcutaneous infusion of the new bradykinin antagonist HOE 140 (500 micrograms/kg/day) attenuated the antihypertensive effect of ramipril only in 2K1C hypertensive Wistar rats, but not in 2K1C BN-K rats and SHR. Our data demonstrate for the first time that potentiation of endogenous kinins contributes to chronic antihypertensive actions of ACE inhibitors in experimental renal hypertension. Whether this holds also true for other forms of hypertension remains to be answered.
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PMID:Role of bradykinin in chronic antihypertensive actions of ramipril in different hypertension models. 128 37

Nitric oxide (NO) plays an important role in the regulation of coronary vascular resistance. The aim of the present study was to evaluate the role of NO in the regulation of coronary vascular resistance in isolated hearts from normo- and hypertensive rats, which served as a model for arterial hypertension and hypertensive heart disease. Isolated hearts from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were perfused at constant flow, whereas the release of NO into the coronary circulation was measured simultaneously by the oxyhemoglobin technique. Bradykinin, an endothelium-dependent vasodilator, concentration-dependently decreased the coronary perfusion pressure in SHRs by 47 +/- 3% and in WKY rats by 35 +/- 6%. In parallel, the basal NO release increased in both groups, maximally by 154 and 118 pmol/min in SHRs and WKY rats, respectively. Amounts of released NO were sufficient to account for the bradykinin-induced coronary vasodilation. These data indicate that coronary resistance vessels in hearts from hypertensive compared to normotensive rats exhibit a higher sensitivity to the endothelium-dependent vasodilator bradykinin, paralleled by a higher release of NO into the coronary circulation. An enhanced endothelial NO synthesis within the coronary circulation may represent a compensatory mechanism aimed at counterregulating distinct changes in vascular reactivity occurring in arterial hypertension.
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PMID:The role of nitric oxide in the regulation of coronary vascular resistance in arterial hypertension: comparison of normotensive and spontaneously hypertensive rats. 128 63

Bradykinin caused graded contractions of rings of rabbit aorta and jugular vein with EC50 values of 1.3 microM and 2.2 nM. In denuded preparations, responses of bradykinin in jugular vein but not in aorta were potentiated 1,000-fold. Both preparations bathed in calcium-free solution showed markedly depressed responses to bradykinin, but addition of 1 mM EGTA further inhibited bradykinin responses only in aorta. Time-course experiments carried out in calcium-free solution plus EGTA revealed that bradykinin contractions in rabbit aorta were very sensitive to extracellular calcium, whereas responses of the jugular vein depended on both extracellular and intracellular calcium sources. Responses to bradykinin in both tissues were unaffected by nicardipine (1 microM) but were partially antagonized by NiCl2 (0.1-0.3 mM). Ryanodine (30 microM) incubated in calcium-free medium markedly inhibited jugular vein responses to bradykinin but had no effect on aortic responses. Phorbol ester (1 microM) caused a slow tonic contraction in jugular vein but not in aorta and inhibited bradykinin responses in the former preparation. Staurosporine (1-100 nM) and 1-(5-isoquinolinesulfonyl)-2-methylpiperizine (H-7, 3 and 10 microM) caused a dose-dependent inhibition of bradykinin-induced contractions in jugular vein but were less effective in aorta.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1992 Feb
PMID:Effect of protein kinase C and calcium on bradykinin-mediated contractions of rabbit vessels. 131 Apr 85

1. The kinin antagonist des-Arg9-[Leu8]bradykinin, injected into the lateral ventricle, caused a long-lasting, dose-dependent reduction in arterial blood pressure and heart rate in spontaneously hypertensive rats but not in normotensive Wistar-Kyoto rats; the antagonist also blocked the pressor response to ventricularly infused bradykinin in both strains. 2. Bradykinin content was increased in the hypothalamus and septum and decreased in the dorsal medulla of spontaneously hypertensive rats when compared with those of normotensive Wistar-Kyoto rats, whereas similar bradykinin contents were observed in the pineal gland, hypophysis and rostroventrolateral medulla of both rat strains. 3. Increased concentrations of bradykinin and its precursor kininogen were found in the cerebrospinal fluid of spontaneously hypertensive rats. 4. Bradykinin receptor numbers, measured as the binding of [125I-Tyr1]bradykinin to nervous tissue, were found to be increased in the dorsal medulla and hypophysis, and to be decreased in the pineal gland, of spontaneously hypertensive rats. 5. Therefore, the central kinin system may participate, by both pre- and post-synaptic mechanisms, in the maintenance of hypertension in spontaneously hypertensive rats.
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PMID:Central bradykininergic system in normotensive and hypertensive rats. 131 60

The contribution of endogenous kinins to the chronic antihypertensive effect of angiotensin converting enzyme inhibitors was investigated in two-kidney, one clip hypertensive Wistar rats, using the new bradykinin B2-receptor antagonist HOE 140 (D-Arg, [Hyp3, Thi5, D-Tic7, Oic8]-bradykinin). In a first protocol, rats were pretreated orally with the angiotensin converting enzyme inhibitor ramipril (1 mg/kg per day), for 4 weeks. Acute blockade of bradykinin receptors by intravenous injections of HOE 140 at doses of 8.4 and 100 micrograms/kg, which inhibited the depressor responses to exogenous bradykinin, did not affect the antihypertensive effect of ramipril in these animals. Bradykinin receptors were then blocked chronically by subcutaneous infusion of HOE 140 (500 micrograms/kg per day) via osmotic minipumps for 6 weeks, while ramipril treatment was continued. HOE 140 partially reversed the antihypertensive effect of ramipril from 115.3 +/- 4.6 to 123.8 +/- 3.3 mm Hg (mean arterial blood pressure) after 3 weeks and to 121.3 +/- 2.9 mm Hg after 6 weeks. In contrast, in controls (ramipril plus subcutaneous vehicle infusion) mean arterial blood pressure decreased further from 112.0 +/- 6.0 to 110.3 +/- 4.9 mm Hg after 3 weeks and to 103.7 +/- 5.0 mm Hg after 6 weeks (p less than 0.05 and p less than 0.01, HOE 140 versus controls). Plasma catecholamines were not significantly different between the two groups at the end of the experiment, indicating that the partial reversal of the antihypertensive effect was not due to a bradykinin-like agonistic effect on catecholamine release.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1992 Jul
PMID:Chronic kinin receptor blockade attenuates the antihypertensive effect of ramipril. 131 60


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