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

Serum concentration of erythropoietin (EP) was measured with a hemagglutination inhibition technique and plasma renin activity (PRA) with a radioimmunoassay for angiotensin I in 26 renal transplant recipients 2-54 months after renal transplantation. In all patients, the EP values were significantly correlated with the levels of PRA (r = 0.76 p less than 0.001) and hematocrit values (r = 0.72, p less than 0.001). In one patient, erythrocytosis and high blood pressure associated with high EP and PRA levels disappeared after bilateral nephrectomy of his own kidneys. The results indicate an as yet unidentified relationship between the production of EP and renin.
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PMID:Erythropoietin and renin after renal transplantation. 78 10

Recently, the availability of a number of specific inhibitors of the renin-angiotensin system has made it possible to address certain critical questions concerning the role of angiotensin II in physiologic homeostasis and in a number of pathologic states. These studies indicate that angiotensin II does not have an obligatory role in blood pressure maintenance in the normal, sodium replete individual, but it is essential following sodium depletion. The role of angiotensin II in feedback control of renin secretion is confirmed as is its importance in aldosterone stimulation both in relation to posture and sodium depletion. Angiotensin II is responsible for the initial pressor response of experimental renovascular hypertension and appears to be important in the initiation of chronic renovascular hypertension. Converting enzyme blockers and competitive inhibitors of angiotensin II are helpful in the diagnosis of clinical renovascular hypertension and in the identification of renin dependent hypertensives. Homeostatic mechanisms leading to maintenance of blood pressure and accumulation of edema in experimental congestive heart failure appear to be dependent on angiotensin II.
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PMID:George C. Griffith lecture. The role of renin in normal and pathological cardiovascular homeostasis. 79 34

The purpose of this study was to determine whether increased sympathetic nervous system activity with proportionally greater stimulation to the kidney could result in sustained hypertension. This was simulated by continuous intrarenal norepinephrine infusion. Effects of chronic infusion of norepinephrine (0.285 microng/kg per min) into the renal artery and inferior vena cava were compared in uniephrectomized conscious dogs. Ten days of intrarenal norepinephrine infusion produced a sustained rise in mean arterial pressure (25 mm Hg), and a 32-mEg positive sodium balance occurred. Inferior vena caval infusion caused a transient rise, lasting 24 hours, in mean arterial pressure which was associated with a 54-mEq natriuresis. With renal artery infusion, peripheral plasma renin activity rose from 1.0 +/- 00.2 to 4.4 +/- 0.8 ng angiotensin I/ml per hour at 1 hour (P less than 0.002) and fell to 1.4 +/- 0.4 at 24 hours (not significant). Inferior vena caval infusion produced a similar result. [Sar1,ala8]angiotensin II (6 MICrong/kg per min) produced no significant change in arterial blood pressure. (alpha-Adrenergic blockade with phentolamine normalized the blood pressure. Renal plasma flow was chronically decreased by about 25% in dogs given intrarenal norepinephrine; no significant change in glomerular filtration rate occurred. The cardiac output decreased from a control of 7.2 +/- 0.6 to 4.8 +/- 0.1 liters/min (P less than 0.01) and total peripheral resistance was increased from a control of 13 +/- 1 to 26 +/- 1 resistance units (RU) (P less than 0.0005) in dogs given intrarenal norepinephrine. The data indicate that chronic intrarenal infusion of norepinephrine in uninephrectomized conscious dogs results in sustained hypertension characterized by decreased renal plasma flow, normal glomerular filtration rate, positive sodium balance, and increased total peripheral resistance due to norepinephrine-dependent vasoconstriction.
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PMID:Production of sustained hypertension by chronic intrarenal norepinephrine infusion in conscious dogs. 87 Feb 20

Eighteen patients with advanced or malignant hypertension due to essential hypertension, systemic lupus erythematosus or chronic glomerulonephritis were infused intravenously with 1-Sar-8-Ile-Angiotensin II, a competitive antagonist of aniotensin II. The spectrum of responses was broad from a mild elevation to a marked fall in blood pressure. The changes in mean blood pressure caused by this peptide showed a significant correlation with the level of peripheral plasma renin activity immediately before the infusion (r=0.5652, p less than 0.02). This peptide infusion reduced blood pressre in 12 patients (responders), but not in 6 (non-respnders). There were no differences with age, sex and severity of hypertension except for the level of peripheral plasma renin activity between the two groups. Our retrospective study showed that in 12 responders propranolol reduced blood pressure to near the normal level, while in 6 non-responders furosemide induced similar depressor response. It is concluded that the vasodepressor effect of this peptide correlates with the levels of peripheral plasma renin activity and that the responses to this drug can be used as a guide for the selection of effective antihypertensive drugs.
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PMID:Clinical evaluation of angiotensin II antagonist in advanced hypertension. 88 41

Patients with essential hypertension were sodium deprived by five days on a 10 mM sodium diet and were then infused with an incremental infusion of saralasin, a competitive inhibitor of angiotensin II. Patients with normal renin hypertension showed no change in lying or standing blood pressure during the infusion of saralasin. Angiotensin II is not, therefore, directly maintaining blood pressure in these patients when sodium deprived by diet, and is therefore unlikely to be playing any direct role in maintaining their blood pressure on their normal sodium intake. Patients with low renin hypertension showed a significant rise in blood pressure during saralasin infusion. Saralasin may be a further method of distinguishing low renin hypertensives from other hypertensives if they are infused when sodium deprived by diet.
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PMID:Angiotensin II blockade in patients with essential hypertension. 107 4

1. The metabolic role of arterial angiotensin I-forming enzyme (i.e. renin activity) was studied in total homogenates and in subcellular fractions of the aorta of normotensive and hypertensive rats. 2. Angiotensin I-forming enzyme was measured in (a) uninephrectomized rats rendered hypertensive with D-aldosterone and sodium chloride (10 g/l drinking solution, (b) rats treated in the same manner but with the addition of spironolactone, and (c) control rats. 3. Hypertension developed in aldosterone-treated rats within 3-6 weeks and was associated with decreased plasma and renal renin values. Total aortic renin activity was up to sixfold higher in the hypertensive animals than in control animals and there was an increased ratio of supernatant to microsomal renin activity in the aorta. 4. In spironolactone-treated rats blood pressure and total aortic renin concentrations were comparable with those in the control rats. 5. The results support the hypothesis that renin generated at local vascular sites, which is independent of circulating renin levels, contributes to regulation of blood pressure.
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PMID:Effects of aldosterone and spironolactone on arterial renin in rats. 107 85

1. The arteriolar lesions of rats with deoxycorticosterone (DOCA)-salt hypertension have been studied by colloidal carbon injection and light- and electron-microscopy. 2. Colloidal carbon particles enter the media of arterioles to form focal deposits when hypertension develops. 3. The focal lesions are similar to those seen after angiotensin infusion or renal artery constriction. They are characterized by endothelial damage and plasma deposition in the media. 4. Heavy deposition of carbon in the glomeruli of DOCA-treated animals was found to be caused by increased mesangial uptake and not by hypertensive vascular damage. 5. Angiotensin II concentrations fell during the development of hypertension and vascular lesions. The renin-angiotensin system was not implicated in the development of vascular damage in this form of hypertension.
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PMID:The arteriolar lesions of steroid hypertension in rats. 107 33

A review of some recent laboratory findings indicates definite disturbances in aldosterone metabolism and regulation in patients with mild essential hypertension: (a) a significant mean increase in plasma aldosterone concentration in patients with mild and stable essential hypertension, in contrast to the absence of any difference in patients with labile borderline essential hypertension when in a normotensive phase, compared with control subjects; and (b) a significant mean decrease in metabolic clearance rate of aldosterone, associated with a 12% decrease in hepatic blood flow and an increased binding of aldosterone to a transcortin-like plasma globulin. The secretion rate of 18-hydroxy-11-deoxycorticosterone is above the upper range of normal in 60% of patients with mild, uncomplicated essential hypertension. The incidence of low-renin hypertension, when age and race are taken into account, is much lower than previously assumed. Unless measurements are repeated over a long period, one or two low values of plasma renin cannot be considered a permanent marker indicating a special category of patients with essential hypertension. Tonin, a new enzyme discovered by Boucher, which forms angiotensin II directly from a plasma protein, from the tetradecapeptide substrate and from angiotensin I, is present in most tissues, but in highest concentration in the submaxillary gland. This enzyme is under the control of beta-adrenergic receptors.
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PMID:Aldosterone and renin in essential hypertension. 109 56

The responses of blood pressure, plasma renin activity (PRA) and plasma aldosterone concentration (PAC) to infusion of either angiotensin II (10 ng/Kg/min) or norepinephrine (100 ng/Kg/min) were observed in 25 patients with essential hypertension. The difference in modes of response between low renin essential hypertension and normal or high renin essential hypertension was analyzed. For comparison, 5 patients with Conn's syndrome, 4 with renovascular hypertension, and 5 normotensive subjects were also studied. Following infusion of antiotensin II the changes in diastolic blood pressure (DBP) were +24+/-3.0 mmHg in low renin essential hypertension and +25+/-3.1 mmHg in normal or high renin essential hypertension in PRA -0.28+/-0.06 ng/ml/h in low renin essential hypertension and -0.69+/-0.02 mg/ml/h in order and in PAC +3.7+/-1.4 and +7.6+/-1.8 ng/100 ml respectively. There was a significant difference in magnitude of response in PRA between the 2 groups of essential hypertension (p less than 0.05). Norepinephrine induced rise in DBP with decreases both in PRA and PAC. The mean changes in DPB were +6+/-1.4 mmHg in low renin essential hypertension and +16+/-2.2 mmHg in another and the pressor response in the later was significantly greater (p less than 0.01). The changes in PRA were -0.14+/-0.07 ng/ml/h in low renin essential hypertension and -0.67+/-0.26 ng/ml/h in normal or high renin essential hypertension, and in PAC -4.9+/-1.3 and -3.3+/-1.9 ng/100 ml respectively. The greater fall in PRA in normal or high renin essential hypertension was observed but the difference between the 2 groups of essential hypertension was not significant. The changes in PAC did not parallel the changes in PRA. Angiotensin II indcued essentially similar effects on blood pressure in both groups but the greater feedback inhibition of PRA was produced by this peptide in normal or high renin essential hypertension than in low renin essential hypertension. Norepinephrine induced significantly greater pressor effect in normal or high renin essential hypertension. The adopted dose of norepinephrine suppressed both PRA and PAC and a tendency to the greater fall in PRA was observed in normal or high renin essential hypertension. There was no difference in responses of PAC to both agents between the 2 groups of essential hypertension.
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PMID:Effect of pressor agents on blood pressure, plasma renin activity and plasma aldosterone concentration in essential hypertension. 115 95

To explore the molecular and subcellular effects of Angiotensin II during the early phase of an experimental hypertension, biochemical and morphological changes induced by continued administration of subpressoric Angiotensin II doses were traced in rats. After the treatment, the endogenous noradrenalin and dopamine content was changed in various brain regions, the turnover rate of noradrenalin was lowered, and the neuronal 3H noradrenalin uptake was delayed and reduced. Electron microscopy revealed an increase in number and granulation of adrenergic vesicles in the hypothalamus, and characteristic changes at pre- and postsynaptic membrane complexes. The interaction between central effects of angiotensin II and the adrenergic system presumably involves disturbance at the level of neuronal membranes.
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PMID:[The mechanism of action of peptides acting on smooth muscle. II. Relationships between angiotensin II and adrenergic systems with reference to blood pressure regulation]. 118 40


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