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

Cellophane perinephritis hypertension was produced in four dogs, while five additional dogs served as normotensive controls. A competitive antagonist of angiotensin II, 1-sarcosine-8-alanine angiotensin II, was infused iv into these conscious dogs at a rate of 6 mug/min/kg of body weight for 45 min. Arterial pressure averaged 170 +/- 11 (SEM) mm Hg in the dogs with perinephritic hypertension, and was not altered significantly during infusion of the angiotensin antagonist. In the normal dogs the arterial pressure averaged 100 +/- 10 mm Hg and likewise, did not change during administration of the angiotensin analog. Plasma renin activity values were essentially the same in these two groups of dogs and did not change during infusion of the angiotensin antagonist. These studies provide strong evidence that the renin-angiotensin system is not involved in maintaining the elevated arterial pressure in dogs with chronic hypertension produced by cellophane perinephritis.
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PMID:Role of the renin-angiotensin system in dogs with perinephritis hypertension. 96 86

Renin activities were determined in plasma and in single, microdissected juxtaglomerular apparatus in 19 patients with unilateral renal artery stenosis. The mean juxtaglomerular apparatus renin concentration in the stenosed kidneys was 5.5 +/- 1.2 (SEM) mug.l-1.h-1 which is about ten times that of the suppressed renin concentration in the contralateral kidneys (0.6 +/- 0.05 mug.l-1.h-1). On the affected side a positive correlation was found between intrarenal and renal venous renin concentration (r = 0.93; p less than 0.001). Both intrarenal and renal venous renin concentrations of the stenosed kindeys were positively correlated to renin secretion rates, as calculated from renin analysis in plasma from the vena cava and renal veins. No relationship could be demonstrated between intrarenal or renal venous renin concentration and the degree of blood pressure elevation or transstenotic pressure gradient. However, a positive correlation was evident between peripheral plasma renin activity and diastolic blood pressure (r = 0.88; p less than 0.001). Comparative enzyme kinetic analyses of renin from the juxtaglomerular apparatus and renal venous plasma were performed using sheep substrate. The lowest apparent Km-values of renin were found in renal venous plasma from the stenosed kidneys (198 +/- 13 mug/l) compared with the contralateral side (301 +/- 20 mug/l; p less than 0.001). Mean apparent Km-values of juxtaglomerular apparatus renin in the stenosed (270 +/- 36 mug/l) and contralateral (292 +/- 37 mug/l) kidneys did not differ. No significant differences were found between mean apparent Km-values for renin in peripheral plasma of renovascular hypertensive patients and control subjects using either homologous human or heterologous sheep renin substrate. The results suggest that, in addition to the renin concentration other factors are relevant to chronic high blood pressure in renovascular hypertension.
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PMID:Kidney and plasma renin in human renovascular hypertension. 100 43

1. Indomethacin inhibits prostaglandin synthesis and interferes with renin release; these effects were studied in rabbit renovascular hypertension. 2. Ten intravenous injections (3 mg day-1 kg-1 after two initial doses of 9 mg/kg) of indomethacin were given daily to ten normal rabbits, ten rabbits with two-kidney Goldblatt hypertension (2KH), tension (1KH). Twelve appropriate control rabbits received diluent phosphate buffer without indomethacin. Plasma renin activity and plasma prostaglandin E2 were measured by radioimmunoassay. 3. In the normal group, indomethacin significantly decreased plasma prostaglandin E2 (1-15 to 0-2 ng/ml, SEM 0-2; P less than 0-01) and plasma renin activity (20 to 3 ng h-1 ml-1, SEM 1, P less than 0-01). Plasma creatinine increased slightly but the mean blood pressure was not significantly changed by indomethacin. 4. Six of ten rabbits with 2KH showed results similar to those in the normal rabbits. In four of ten rabbits in which development of 2KH was accompanied by increments in plasma renin activity (18 to 31-5 ng h-1 ml-1, SEM 3 and 4 respectively; P less than 0-01) and plasma prostaglandin E2 (1-2 to 3-4 ng/ml, SEM 0-2 and 0-4 respectively; P less than 0-05), treatment with indomethacin produced renal failure (plasma creatinine increasing to 7-6 mg/100 ml), oliguria, malignant hypertension (mean blood pressure, 168 mmHg, SEM 7-7) and death within 5 days. 5. In 1KH, indomethacin decreased plasma renin activity and plasma prostaglandin E2, but caused increased mean blood pressure (102 to 121 mmHg, SEM 4 and 6 respectively; P less than 0-01) and decreased renal function (plasma creatinine 0-9 +/- 0-04 to 3-5 +/- 1 mg/100 ml, SEM 0-04 and 1 respectively; P less than 0-01). 6. Aggravation of hypertension was conditioned by pre-existing levels of renal function and, to a lesser extent, by plasma renin activities. 7. These results suggest that prostaglandins exert a protective effect on renal function in renovascular hypertension.
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PMID:Effects of indomethacin in rabbit renovascular hypertension. 107 20

1. The National Blood Pressure Study (NBPS) is a single blind trial designed to test the efficacy of active drug treatment in reducing complications from mild hypertension (mean diastolic pressure = 95-109 mmHg). 2. Between 1973 and 1975, four centres screened about 104 000 subjects aged 30-69 years, yielding an estimated prevalence of hypertension (greater than or equal to 95 mmHg diastolic) of 16% and of moderate-to-severe hypertension (greater than of equal to 110 mmHg diastolic) of 1-3%. 3. Some 4000 subjects selected for untreated uncomplicated mild hypertension were randomized to either active treatment (cholorothiazide +alpha-methyldopa and/or a beta-adrenoreceptor antagonist as required) or to matching placebos. 4. At 1 year mean pressures had fallen significantly below entry pressures in both groups but in the active group the fall was greater by a margin of 14-4+/-1-3 (SEM) mmHg systolic and 7-1+/-0-7 mmHg diastolic. At 1 year 5% of subjects in the placebo group had been placed on active treatment on the ethical grounds that pressure had exceeded the mild hypertension limit. 5. Trial end-points (death, morbidity from stroke, hypertensive heart and renal disease, and ischaemic heart disease) number 106 (nine deaths) thus far, of which ischaemic heart disease accounts for 71% and stroke 19%. 6. The duration of trial may need to be extended beyond the original estimate of 5 years.
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PMID:Report on progress in the Australian National Blood Pressure Study (NBPS). 107 98

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

To examine whether atrial natriuretic factor (ANF) is secreted adequately in the early phase of myocardial infarction, plasma ANF concentration and clinical parameters, including hemodynamic variables, were studied in 118 patients with acute myocardial infarction (AMI). The patients were divided into 2 subgroups according to the absence (group A, n = 41) or presence (group B, n = 77) of a history of valvular heart disease, previous myocardial infarction, hypertension, or renal failure. Although no significant difference in atrial pressure after the infarction was found between the 2 groups, the plasma ANF level was significantly lower in group A than in group B (76 +/- 6 vs. 185 +/- 26 pg/ml; mean +/- SEM, p < 0.01). Plasma ANF was correlated with pulmonary capillary wedge pressure in group B (r = 0.54, p < 0.001), whereas no relationship with hemodynamic parameters was observed in group A. In 56 of the 118 patients (group A, n = 18; group B, n = 38), the pulmonary arterial plasma level was significantly higher in group A (p < 0.05), whereas the difference was not significant in group B. Seven of the 8 expired cases among these 56 patients had peripheral plasma ANF levels of more than 150 pg/ml, which were higher than those in pulmonary arterial plasma. These observations suggest firstly that the plasma level of ANF is lower in patients with a new onset of myocardial infarction compared to those with a history of cardiac or renal diseases, and secondly that stimulated ANF release originates not only from the right side of the heart, but also from additional site(s), particularly in patients with chronic ventricle overload and a poor prognosis.
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PMID:Plasma atrial natriuretic factor in patients with acute myocardial infarction. 128 94

Traumatic brain injury causes alterations in cerebral blood flow that are thought to influence secondary pathophysiology and neurologic outcome in humans. Since it is difficult to study early changes in blood flow in head-injured patients, animal models of brain injury must be employed. However, techniques to monitor brain blood flow in animals are labor intensive and generally provide discontinuous flow measurements. The present study examines the application of laser-Doppler flowmetry for measurement of cerebral blood flow following experimental brain injury. This method allows continuous monitoring of local cerebral blood flow before, during, and after injury. Rats (n = 9) were prepared for lateral fluid percussion injury under barbiturate anesthesia. Injury (2.10 +/- 0.02 atm) was induced over the right parietal cortex, and blood flow was monitored in the contralateral cortex. Seconds after the peak hypertension after injury, blood flow in the left parietal cortex increased 226% +/- 18% (means +/- SEM). This increase was transient, with blood flow falling below control values within minutes. Five minutes after injury, blood flow was 83% +/- 8% of control, and at 1 h, this value had fallen to 56% +/- 6%. Blood flow at 60 min was 93% +/- 5% of control in the sham-injured group (n = 10). The reduction in cerebral blood flow in our laser-Doppler study was of similar magnitude as previously reported in rats injured at a similar intensity when blood flow was examined with radiolabeled microspheres. Given these results, we believe laser-Doppler flowmetry can be used to continuously monitor posttraumatic blood flow following experimental brain injury.
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PMID:Continuous monitoring of posttraumatic cerebral blood flow using laser-Doppler flowmetry. 129 95

To examine the role of mineralocorticoids in the pathophysiology of pregnancy-induced hypertension (PIH), we studied plasma aldosterone and 18-hydroxycorticosterone levels in 25 women with PIH and 25 normal pregnant women, as controls. Furthermore, we evaluated the mineralocorticoid receptor (MR) status in mononuclear leukocytes in the 2 groups. MR count was significantly (P less than 0.0005) decreased in the PIH group (148 +/- 9 binding sites/cell) compared with the control group (300 +/- 17 binding sites/cell; mean +/- SEM). Plasma aldosterone in women with PIH was 281 +/- 61 pmol/L; in normal pregnant women it was 697 +/- 172 pmol/L (P less than 0.025). Plasma 18-hydroxycorticosterone was also significantly (P less than 0.025) lower (PIH, 1071 +/- 149 pmol/L; controls, 1907 +/- 318 pmol/L). These values were determined at the onset of clinical symptoms of PIH. These results cannot be explained by receptor down-regulation due to higher levels of mineralocorticoids in PIH; a hitherto unknown mineralocorticoid may, thus, be responsible for the hypertension and altered MR status.
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PMID:Mineralocorticoids and mineralocorticoid receptors in mononuclear leukocytes in patients with pregnancy-induced hypertension. 131 41

To investigate the pathophysiology of hypertension in patients receiving recombinant human erythropoietin (rHuEpo) we studied its effects on the renin-aldosterone axis of chronic haemodialysis (HD) patients not receiving antihypertensive drugs. Nine severely anaemic normotensive HD patients received rHuEpo 50 U/kg bodyweight, thrice weekly after each HD. The dose was increased by 25 U/kg bodyweight every 4 weeks to a maximum of 100 U/kg or until an increase of Hb or Hct of 2 g/dl or 7% was achieved. Blood samples were taken after 30 min supine rest and while seated 10 min later after gentle ambulation. Results expressed as mean +/- SEM: therapy in normotensive HD patients by a negative feedback loop, before the development of hypertension.
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PMID:Suppression of the renin-angiotensin-aldosterone axis with erythropoietin therapy by a negative feedback loop. 131 71

1. In normotensive Wistar (W) and spontaneously hypertensive (SHR) rats between 5 and 20 weeks of age, there was an age-related increase in blood pressure (r2 = 0.770 and r2 = 0.801 respectively). Except for adrenaline (r2 = 0.979) in SHRs, plasma catecholamines and age were unrelated. 2. In ring segments of thoracic aorta from 5, 10, 15 and 20 week old rats, the respective EC80s (-log M) for phenylephrine (PE)-induced contractions were 8.20 +/- 0.37, 7.96 +/- 0.10, 7.15 +/- 0.12 and 7.12 +/- 0.21 in W and 7.73 +/- 0.13, 7.72 +/- 0.16, 7.37 +/- 0.08 and 7.40 +/- 0.03 in SHR tissues (means +/- SEM; n = 5-7). 3. In PE-preconstricted rings, the respective EC50s (-log M) for isoprenaline (IPNA)-induced relaxation were 7.97 +/- 0.11, 7.74 +/- 0.10, 6.96 +/- 0.19 and 6.57 +/- 0.26 in W and 8.03 +/- 0.24, 7.62 +/- 0.08, 6.88 +/- 0.13 and 6.73 +/- 0.14 in SHR tissues (n = 5-7). 4. In PE-preconstricted rings from 5 and 20 week old rats, a single concentration of IPNA (approximating the respective IPNA EC50s) induced relaxation which was sustained over 2 h in W but not SHR tissues. The SHR:W ratios of the net relaxant responses, at 5 and 20 weeks, were 0.6461 and 0.6167 respectively. 5. Thus, W rats exhibit an age-related loss in both vascular alpha- and beta-adrenoceptor responsiveness which appears unrelated to plasma catecholamines. SHRs also exhibit an age-related loss in vasodilator beta-adrenoceptor responsiveness, which may involve adrenaline-induced desensitization, but appear to maintain vasoconstrictor alpha-adrenoceptor responsiveness. It is proposed that an age-related decline in beta-adrenoceptor responsiveness coupled to maintenance of alpha-adrenoceptor responsiveness may lead to chronic blood pressure elevation, as observed in SHRs, while a parallel decline in both alpha- and beta-adrenoceptor responsiveness, as observed in W rats, may preclude hypertension development.
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PMID:Vascular beta-adrenoceptor-mediated responses in hypertension and ageing in rats. 133 55


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