Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe a sensitive, simplified radioimmunoassay method for determination of plasma renin activity. Plasma was acidified to the optimal pH (6.0) of angiotensin l generation with the least possible dilution, by using a single addition of hydrochloric acid and the enzyme inhibitor hydroxyquinoline. Recovery of unlabeled angiotensin l added to plasma was 92-97%; that of monoiodinated angiotensin l exceeded 90%, indicating satisfactory protection from proteolytic enzymes. Plasma constituents interfered little with the radioimmunoassay. Bland values for plasma kept at 0 degrees C were 10.7 +/- 2.3 (mean +/- SD) percent of the activity values for samples kept at +37 degrees C (n equals 63). In the routine setting, 6.25 pg of angiotensin l or 10(-6) Goldblatt units of Standard Human Renin was detected. We report results of plasma renin activity measurements and a comparison with seven renin kits, and with bioassay for plasma renin activity.
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PMID:Radioimmunoassay of plasma renin activity. 1866 47

Performance of accurrate, reproducible, and interpretable assays for plasma renin activity and other components of the renin/angiotensin system in the clinical setting requires a clear understanding of the various reactions in the renin/angiotensin cascade and the nature of their interactions. Plasma renin activity, the rate of angiotensin generations from plasma incubated in vitro, is the most commonly used clinical index of function in the renin/angiotensin system. Renin activity is measured by radioimmunoassay of angiotensin I generated in vitro under carefully controlled conditions. The value obtained for plasma renin activity depends on pH and duration of incubation and on the method used to protect the angiotensin I generated. We recommend incubation at neutral pH in buffered plasma for three hours in the presence of either ethylenediaminetetraacetate + 8-hydroxyquinolone + dimercaprol or ethylenediaminetetraacetate + phenylmethylsulfonylfluoride. Addition of a standard preparation of human renin to the plasma incubation step of the renin activity assay serves the dual purpose of permitting measurement of renin activity and furnishing an internal standard for comparison of assay procedures. The many variables among renin assay methods can be cancelled by referring to a common internal renin standard.
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PMID:Theoretical approaches to estimation of plasma renin activity: a review and some original observations. 0 37

Renin granules from rat kidney prepared at 25 degrees C show greater stability at 25 degrees C than at 0 degrees C when incubated in ionic medium. The sum of the renin in the supernatant fluid plus that in the pellet was the same at 25 degrees C as at 0 degrees C, thus ruling out the possibility that the extra release at 0 degrees C merely represented greater stability of free renin at 0 degrees C. In common with other secretory granules, renin granules were most stable at pH 6.0 and were osmotically sensitive. In contrast to neurosecretory and chromaffin granules, renin granules were stabilized by Mg-ATP in ionic medium. This result is similar to studies by others on lysosomes. It is concluded that the renin granules membrane shares many of the properties of other granule membranes. Some of these properties (temperature and pH lability) will have to be considered in the design of future experiments on renin storage and release.
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PMID:Properties of renin granules isolated from rat kidney. 1 Feb 15

Patients suffering from pheochromocytoma characterized by an exclusive or almost exclusive excess of norepinephrine showed no (one patient) or only a moderate increase (two patients) in renin and aldosterone secretion. In those three patients with concomitant distinct hypersecretion of epinephrine, renin release (and aldosterone secretion except in one patient) was markedly enhanced. Similar results were obtained in a patient with excess norepinephrine and dopamine secretion. Renin release was markedly reduced in all patients during preoperative long-term alpha-adrenergic receptor blockade. With the exception of one patient, increased renin and aldosterone secretion was abolished. The results indicate that augmentation in renin release depends on the ratio of the different catecholamines secreted by the pheochromocytoma and their different effe-tiveness in stimulating beta-adrenergic receptors. Even in the presence of excess catecholamine secretion, there is evidence that renin secretion is predominantly mediated by beta receptors rather than by renal vascular alpha-adrenergic receptors. Normalization of catecholamine-induced enhanced renin release in patients with pheochromocytoma during chronic alpha-adrenergic receptor blockade supports the assumption that (alpha-) adrenergic blocking agents inhibit renin secretion distal to their blockade of specific adrenergic receptors. However, contrary to beta-adrenergic blockade, circadian rhythm of renin release seems to remain intact during alpha-adrenergic blockade.
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PMID:Renin and aldosterone secretion in pheochromocytoma. Effect of chronic alpha-adrenergic receptor blockade. 1

The pressor enzyme renin (EC 3.4.99.19) was isolated in a pure and stable form from hog kidney by affinity chromatography on a pepstatin/agarose gel followed by three additional steps of conventional chromatography. Destruction of the enzyme by proteolysis during isolation was prevented by chemically eliminating proteases in extracts. The pure preparation was used for the characterization of this enzyme. Renin was found to be a glycoprotein containing glucosamine and possessing binding affinity to concanavalin A. Contrary to previous reports, pure renin is stable at neutral pH either at 4 or -20 degrees for 3 to 8 weeks. It has a molecular weight of 36,400 as determined by equilibrium ultracentrifugation, an isoelectric point of 5.2 and E1%1cm (280 nm) of 9.1. In contrast to crude preparations, the enzyme activity has a broad pH optimum between pH 5.5 and 7.0 for both hog angiotensinogen and the synthetic octapeptide substrate benzyloxycarbonyl-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser-beta-naphthylamide. The rate of formation of angiotensin I from hog angiotensinogen at pH 6.0 and 37 degrees was 267 microng/h/microng of renin, or 2000 Goldblatt units/mg of renin. For the synthetic fluorogenic octapeptide substrate benzyloxycarbonyl-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser-beta-naphthylamide, a Km of 33 micronM and a Vmax of 0.94 micronmol/h/mg of enzyme were obtained at pH 6.5 and 37 degrees.
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PMID:Pure Renin. Isolation from hog kidney and characterization. 1 12

1. The properties of inactive and active renin in human plasma and amniotic fluid were studied chromatographically. Activation was achieved at pH 3.3 with and without added pepsin. 2. Acid activation of renin was time- and temperature-dependent but was inhibited by dilution of the sample. The dilution effect was corrected by adding pepsin. Such characteristics indicate that activation at low pH is catalysed by intrinsic enzymes. 3. Separation and/or dilution of the activating enzyme during ion-exchange chromatography concealed the eluted position of inactive renin and reduced the amount recovered. Only after full activation of the eluted renin was achieved with added pepsin was a distinct peak of inactive renin exposed. 4. At pH 7.5 inactive renin carried a lower negative charge than the active enzyme. This charge difference was lost after activation. 5. No molecular-weight differences between active, inactive renin or the International Renin Standard were detected by gel filtration. No renin of larger molecular weight was present. 6. These findings will be helpful in purification studies of human inactive renin.
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PMID:The nature of inactive renin in human plasma and amniotic fluid. 2 28

Renin-containing granules isolated by isopycnic zonal centrifugation were partially characterized biochemically. Extracts of the granules were found to have a dual pH optimum at 5.5-6.0 and 7.0-7.5 and possess linear time-dependence of product formation when reacted with homologous renin substrate. Extracts also possessed a first order reaction constant of 0.713 X 10(-2). Treatment of the extracts with ammonium sulfate increased the velocity of the renin/renin substrate reaction though it continued to be linear with respect to time. This partially purified renin preparation was found to have a Km=3.9 X 10(3) ng/ml. Gel filtration of this preparation of renin demonstrated the presence of an active protein with renin activity and a molecular weight of 59,000 daltons in addition to an inactive protein of molecular weight 13, 750 daltons which may be a potential inhibitor of the renin/renin substrate reaction. The former protein or "big renin" may be the storage form or porhormone state of renin within the renin-containing granules of the juxtaglomerular cells.
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PMID:Studies on the characterization of isolated renin-containing granules: the storage form of renin. 2 65

Recent research shows that the renin-angiotensin-aldosterone axis either maintains or causes some or all of the high blood pressure of most patients and demonstrates anew that renin-sodium profiling defines this involvement. Performed with a serum potassium measurement, this now reliable test is useful for primary screening and then, in conjunction with renal vein renin studies or an aldosterone profile, for diagnosis or exclusion of surgically curable renovascular or adrenocortical hypertensions. For the remaining majority with essential hypertension, renin profiling exposes the relative participation of either vasoconstriction or volume factors, thereby guiding simpler, more specific, and predictably effective antirenin or antivolume treatments. Renin profiling identifies those in whom treatment should begin with a beta-blocker as opposed to a diuretic while not infrequently also providing baseline information about severity and prognosis in individual patients.
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PMID:Renin profiling for diagnosis and treatment of hypertension. 3 92

1. Renal cortical homogenates of the dog were subjected to sieve separation, a Nucleopore Filter being used to separate the renin granules. 2. The molecular weight of renin in the granules was estimated to be about 40 000 by gel filtration. Renin was converted into a higher-molecular-weight form (60 000) by mixing with cytosol in the presence of sodium tetrathionate, a thiol inhibitor. 3. When cytosol was pretreated with acid (pH 3.0) or heating (100 degrees C), the molecular-weight conversion did not occur. 4. Cytosol was separated into three parts by gel filtration. Fraction A included substances with a molecular weight of over 47 000, fraction B from 47 000 to 32 000, and fraction C from 32 000 to 15 000. The mixture of renin in the granules with fraction A and sodium tetrathionate resulted in the formation of a higher-molecular-weight form of the enzyme, but no change in molecular weight was detected when renin was mixed with fractions B or C and sodium tetrathionate.
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PMID:Characteristics of a renin-binding substance for the conversion of renin into a higher-molecular-weight form in the dog. 4 66

Renin activity and aldosterone were evaluated relative to potassium levels and lead intoxication in 33 patients with a history of "moonshine" ingestion. Patients were divided into three groups: I, lead intoxicated with hyperkalemia; II, lead intoxicated without hyperkalemia; and III, not lead intoxicated without hyperkalemia. Those in group I demonstrated suppressed plasma renin activity, baseline and after furosemide, and blunted aldosterone responsiveness to furosemide. Plasma renin activity was not different in groups II and III, whereas aldosterone responsiveness was less in group II than in III. Group I patients tended to be older, had lower creatinine clearances, and six of nine had mild hyperchloremic acidosis. Diabetes and cortisol insufficiency were not present. Chronic lead intoxication due to illicit alcohol ingestion is associated with hyporeninemic hypoaldosteronism and hyperkalemia which appear to develop as the lead nephropathy progresses with duration and/or aging.
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PMID:Renin aldosterone system and potassium levels in chronic lead intoxication. 10 94


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