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

We compared methods of classifying hypertension according to plasma renin activity in 54 patients with essential hypertension and examined the validity of using these classifications to choose between two hypotensive drugs. A prospective, double-blind crossover study was used. Normal values for plasma renin activity were established from 111 control subjects. Plasma renin activity was related to race and inversely to age in hypertensive patients (P less than 0.05) but not in normal subjects. Three methods of classification correlated well but did not identify exactly the same renin-suppressed patients. Chlorthalidone produced a greater reduction in blood pressure and restored blood pressure to normal in a larger percentage of patients in both low-renin (59 per cent) and normal-renin (32 per cent) subgroups than propranolol (12 and 16 per cent). Renin determinations are of limited benefit in the choice of therapy for most patients with essential hypertension.
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PMID:Renin profiling in hypertension and its use in treatment with propranolol and chlorthalidone. 77 25

Of 13 patients with severe post-transplant hypertension, in 11 (85%) the hypertension was secondary to TRAS. Surgical correction of arterial stenosis reversed renal failure in 2 patients and cured or improved hypertension in 9 patients. Renin levels from TRV was normal in patients studied and was not useful in predicting surgical success. The patient's own kidneys are not the cause of post-transplant hypertension. Demonstration of an increased renin activity in the patient's own renal veins is not always associated with relief of hypertension by bilateral nephrectomy.
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PMID:Renal artery stenosis in renal transplant recipients. 80 Oct 61

The blood pressure of rabbits with chronic one-kidney hypertension can be lowered to normal by immunization with hog kidney cortex preparations that do not contain renin, thus providing evidence for a new factor essential for the maintenance of an elevated blood pressure. A search for the new factor has led to the discovery of a hypertensive substance which we have named renopressin. Subcutaneous injection of the new substance into normal rabbits produces a delayed, slow increase in blood pressure, and after a few days the development of a moderate hypertension which persists indefinitely. The response of the blood pressure to renopressin is totally unlike that to renin. While the pressor action of renin can be blocked by an angiotensin II antagonist, the hypertension caused by renopressin cannot. Renin can increase the blood pressure of hypertensive rabbits; renopressin has no effect. The blood pressure of hypertensive rabbits and of normal rabbits made hypertensive by injection of renopressin can be lowered to normal by passive immunization with the same antibody preparation. The evidence is consistent with the possibility that renopressin and the agent causing the elevation of blood pressure in hypertensive rabbits are similar or identical.
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PMID:Chronic one-kidney hypertension in rabbits. III. Renopressin, a new hypertensive substance. 84 40

Serial measurements of urinary sodium excretion, sodium space, plasma volume, and plasma renin concentration were made during the development of hypertension in patients who were exposed to an excess of endogenous or exogenous mineralocorticoid activity. Five patients with primary aldosteronism due to adenoma were followed during spironolactone treatment, for 35-55 days after the drug had been stopped, and finally, after surgery. Blood pressure rose continuously after stopping spironolactone. Sodium balance, however, showed an initial phase of sodium gain, followed by a phase of gradual sodium loss. Sodium space and exchangeable sodium rose by 5.0 +/- 0.48 liters/1.73 m2 of body surface area (BSA) (P less than 0.005) and by 865 +/- 97 mEq/1.73 m2 BSA (P less than 0.005), respectively; the values were maximal after 10-15 days, declined afterward, but remained higher than during spironolactone treatment. Plasma and blood volumes rose by 624 +/- 90 ml/1.73 m2 BSA (P less than 0.005) and by 327 +/- 74 ml/1.73 m2 BSA (P less than 0.01), respectively; they were maximal after 20-25 days, and then returned to their initial values. Exchangeable sodium, during the phase of sodium loss, was inversely correlated with the rise in blood pressure (P less than 0.01). Renin fell during the phase of sodium gain, and remained low afterwards. Blood pressure and sodium space declined after surgery, but plasma volume showed no change. The postsurgery values of these parameters were not significantly different from those measured during spironolactone treatment. Two subjects with adrenocortical insufficiency, who were followed for 45-60 days during treatment with dexamethasone and 9alpha-fluorocortisol acetate, also showed a transient rise in sodium space and plasma volume. The results suggest a redistribution of body fluids during development of hypertension. They also suggest that the tendency of body fluid volumes to return to normal is pressure-dependent. The long-term effects of mineralocorticoid excess on the interrelations between pressure, volume, and renin bear some resemblance to the pattern observed in patients with established essential hypertension, i.e., pressure remains elevated despite a decrease of volume, and renin is "inappropriately" suppressed in relation to the sodium and volume status.
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PMID:Volume-pressure relationships during development of mineralocorticoid hypertension in man. 85 75

Plasma renin activity, reninlike activity present at the artery wall, pressor response to exogenous hog renin, renin half-life time, and renin-like activity present at the artery wall 1 hour after injection of renin were measured in conscious rats 1 month after inducing hypertension by renal artery constriction and contralateral nephrectomy (one-kidney hypertension). Plasma renin activity was higher but without statistical significance in one-kidney hypertensive rats when compared with normotensive or sham-operated animals. Renin-like activity present at the artery wall was significantly increased in hypertensive animals only when compared with one-kidney normotensive rats. Pressor responses to renin in one-kidney hypertensive and normotensive rats were of significantly longer duration than in sham-operated animals. The inactivation rate of exogenous renin followed a first-order reaction with a half-life of 6 minutes in sham-operated rats and of 12 minutes in one-kidney hypertensive and normotensive animals. Decreased inactivation of circulating renin could explain the protraction of the pressor response; however, the slope of the regression equation describing the inactivation of renin in all of the rats was steeper than the slope of the pressor response, indicating a dissociation between blood pressure and plasma renin activity. The renin-like activity present at the artery wall 1 hour after injection of renin was determined in the three groups; the arterial tissue of one-kidney hypertensive rats bound more circulating renin than that of normotensive rats and the latter more than that of sham-operated animals, suggesting the participation of this binding capacity in the protraction of the pressor response and in the maintenance of hypertension.
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PMID:Vascular renin-like activity and blood pressure. 87 67

Renin activity, angiotensin-II concentration and venous aldosterone concentration were measured in 20 healthy subjects and 18 hypertensives before and after stimulation of the renin-angiotensin-aldosterone system. The test did not distinguish between the two groups: in the individual case there was no relationship between renin-activity, angiotensin-II concentration and aldosterone concentration in peripheral venous blood. Stimulation of the system without sodium balance is not a reliable screening test for hypertension.
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PMID:[The value of stimulation of the renin-angiotensin-aldosterone system as a screening test for hypertension (author's transl)]. 88 Aug 79

Renin activity in peripheral plasma (PRA), renal cortex and brain tissue (cortex, stem, medulla oblongata) homogenates was studied in a bioassay after Serebrovskaya's modification of the method of Pickens. Fourty-nine spontaneously hypertensive rats (SHR) and 26 normotensive Wistar rats (NWR) were used. The results show that: 1) In spite of very high systolic blood pressure, PRA in SHR is in normal ranges; 2) Renin activity exists not only in the brain of NWR, but in the brain of SHR as well. 3) Renin activity in the different parts of the brain is not equal both in NWR and in SHR. 4) Renin activity in the cortex, the stem and the medulla oblongata of SHR is in normal ranges. 5) Renin activity in the medulla is higher than in other areas of the brain, both in NWR and in SHR, the difference being statistically significant in the latter. 6) No perceptible interrelation between arterial blood pressure, PRA, renal renin activity and renin activity in the cortex, and in the stem of the brain was established. It is suggested that higher renin activity in the medulla oblongata might be considered as an indication of the importance of the brain renin-angiotensin system, and its function in the cerebral (neural) regulation of the cardiovascular system. A causal connection between the renal and the brain renin-angiotensin systems, and the onset and maintenance of hypertension is assumed.
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PMID:Brain and kidney renin-angiotensin activity in spontaneously hypertensive rats. 90 88

Renin studies were done on 2 patients with adenocarcinoma of the kidney and hypertension. In 1 case plasma renin activity was high in the peripheral and renal veins, with a renal vein ratio of 1.7 favoring the side of the tumor. Nephrectomy cured the hypertension and renin values became normal. Tissue renin was elevated in the tumor and surrounding parenchyma. Acidification studies of tissue extracts failed to demonstrate the existence of big renin. In case 2 all renin values were normal and the blood pressure remained elevated after the operation. Although renin-secreting tumors remain an uncommon cause of malignant hypertension the condition should be recognized because it is potentially curable.
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PMID:Adenocarcinoma of the kidney and hypertension: report of 2 cases with special emphasis on renin. 92 65

To identify patients with low-renin hypertension, we measured plasma renin activity after the administration of 40 mg of furosemide intravenously and 30 minutes of upright posture in 127 normotensive subjects and 363 patients with essential hypertension. Plasma renin activity 30 minutes after intravenous furosemide was found to be closely correlated to the level found after either 2 or 4 h of standing or 3 days of a low-salt diet plus 2 h of upright posture. Renin responsiveness was significantly lower in hypertensive patients, blacks, and women, compared with normotensive subjects, whites, and men respectively. The level of plasma renin activity in most normal white subjects was greater than 1.0 ng/ml - h and in most normal blacks was greater than 0.5 ng/ml - h. It was below those levels in 23% of white hypertensive and 25.2% of black hypertensive patients respectively. The mean level of plasma renin activity fell with increasing age of hypertensive patients. This procedure is recommended as a safe, easy, and reliable test for assessing renin responsiveness and identifying the low-renin state.
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PMID:The intravenous furosemide test: a simple way to evaluate renin responsiveness. 93 75

The cause of oral-contraceptive-induced hypertension in certain susceptible subjects is obscure. We describe a woman who was receiving replacement doses of fludrocortisone acetate after adrenalectomy and hypophysectomy who developed high blood pressure while ingesting an estrogen-containing oral contraceptive. Renin substrate level was increased, but renin activity was suppressed and unresponsive to tilting. The patient developed a markedly exaggerated natriuresis when infused with saline. Both blood pressure and her responses to infused sodium and tilting normalized after discontinuance of the oral contraceptive medication. In this adrenalectomized patient, the estrogenic component of the pill acting synergistically with a fixed ("nonsuppressible") replacement dose of mineralocorticoid seems to have caused a volume-related hypertension.
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PMID:Oral-contraceptive-induced hypertension after adrenalectomy and hypophysectomy. 96 46


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