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

Trypsin cleaved plasma angiotensinogen with apparent first-order kinetics and generated an angiotensin I (Ang I) immunoreactive material. Size exclusion high-performance liquid chromatography (HPLC) of rat plasma proteins demonstrated that the Ang I immunoreactive material was formed in those fractions which contained angiotensinogen. The Ang I immunoreactive material was higher in nephrectomized rat plasma than normal plasma, in accordance with the higher angiotensinogen concentration. These findings indicated that angiotensinogen could be the source of the Ang I immunoreactive material. Purification of the Ang I immunoreactive material by cation-exchange chromatography followed by reverse-phase HPLC demonstrated an elution pattern close to that of human tetradecapeptide. The purified Ang I immunoreactive material was cleaved by pure mouse submandibular renin to Ang I, exclusively. Incubation at 37 degrees C of the Ang I immunoreactive material with plasma partially destroyed the angiotensin immunoreactive material. These findings demonstrated that the angiotensin immunoreactive material was an Ang I containing tetradecapeptide (TDP)-like peptide, unstable during a renin incubation step, leading to erroneous values for plasma inactive renin if not removed. The Ang I immunoreactive material was removed by cation-exchange chromatography of trypsin-activated plasma allowing for a determination of inactive renin. The presence of inactive renin in plasma from normal and nephrectomized rats was confirmed, and identified by neutralization and immunoprecipitation with antirenins. These findings should enable us to develop a routine assay for plasma inactive renin in rat plasma.
 ...
PMID:On the measurement of inactive renin in rat plasma: activation by trypsin generates interfering tetradecapeptide-like material and destroys angiotensinogen. 267 Nov 59

Trypsin activation of rat plasma destroys angiotensinogen and generates a tetradecapeptide-like material, verified by high performance liquid chromatography, which interferes with the measurement of inactive renin. Using an assay based on removal of the material by a cation-exchange resin and the addition of exogenous angiotensinogen, the plasma concentration of inactive renin in intact conscious male rat was 0.48 GU/l (range 0.28-0.67 GU/l, n = 20). Inactive renin comprised about 70% of the total plasma renin. The level of inactive renin was unchanged 24 h after bilateral nephrectomy and 7 days after submandibular sialo-adenectomy. Bilateral nephrectomy of previously sialo-adenectomized rats decreased the level of inactive renin significantly. Our findings are in contrast to the marked increase, reported by several other investigators, in inactive plasma renin in rats following bilateral nephrectomy, and do not support the previously suggested, mainly extrarenal, origin of inactive plasma renin.
 ...
PMID:Solution of methodological problems in measurement of inactive renin in rat plasma using trypsin activation, and the effect of nephrectomy and sialo-adenectomy on inactive plasma renin. 269 32

Inactive renin, prorenin, is found in high concentrations in human plasma. We report herein the characteristics of trypsin-activated inactive renin from cat kidney and plasma. Cat and human plasma inactive renin were activated by similar concentrations of trypsin. As in humans, there was more inactive than active renin in cat plasma; also, inactive renin was low but detectable after nephrectomy. Trypsin-activated renal inactive renin, purified on Cibacron blue agarose and pepstatin-amino-hexyl-Sepharose chromatography, was inhibited by pepstatin and by a renin inhibitor similarly to cat and human active renins. The pH optimum of cat renin was biphasic: the higher peak of active renin was at pH 5.7, whereas that of activated inactive renin was at pH 7.5. As in humans, active and inactive plasma renin increased during sodium depletion and inactive renin increased during beta-adrenergic blockade, while active renin decreased. These results demonstrate that cat inactive renin is similar to human prorenin. Therefore, the cat may be a useful model for the study of prorenin.
 ...
PMID:The cat: an animal model for studies of inactive renin. 288 85

We have examined the effect of trypsin treatment of rat plasma on the rate of angiotensin (Ang) I generation and measurement of this peptide by radio-immunoassay. Trypsin increased the renin incubation blank but did not alter the kinetics of the renin reaction with exogenous renin. The quantity of immunoreactive material detected in trypsin-treated plasma was not proportional to the volume of plasma assayed. Consequently, the level of inactive renin was dependent upon the volume of plasma subjected to the assay. This discrepancy occurred with two independent radio-immunoassay systems. The rate of Ang I generation was linear and significantly elevated following the addition of renin substrate to trypsin-treated plasma. However, if trypsin degradation of endogenous renin substrate was extensive and additional renin substrate was not provided, non-linear rates of Ang I generation occurred. Multiple additions of trypsin were necessary to activate maximally inactive rat plasma renin. Inactive renin accounted for 79 +/- 2% of the total enzyme activity in normal rats. Although active renin declined following bilateral nephrectomy, the ratio of active to inactive renin did not change. The data suggest that the kidney is the primary source of inactive renin in the normal rat.
 ...
PMID:Effects of trypsin on the measurement of inactive renin in rat plasma by radio-immunoassay: decrease in inactive renin following nephrectomy. 328 Jun 72

A simple immunoaffinity column chromatographic procedure is described whereby recombinant human prorenin secreted from Chinese hamster ovary cells may be isolated in a high state of purity from serum-free culture medium. Prorenin thus purified has been characterized by SDS-polyacrylamide gel electrophoresis and by partial sequence analysis which has revealed the expected N-terminal sequence. Trypsin treatment gives rise to renin, and reversible acid activation has also been demonstrated for the recombinant zymogen.
 ...
PMID:Immunoaffinity purification of human prorenin produced in Chinese hamster ovary cells. 328 27

In human plasma samples we compared the values of renin activity, determined with a conventional enzymatic assay, with those of immunoreactive renin, determined with a new, direct immunoradiometric assay which employs highly specific monoclonal antibodies, and with those of angiotensin II; the comparative measurements of renin were carried out also in trypsin activated samples of nephric and anephric subjects. We found that, overall, there was a close relationship between renin activity and immunoreactive renin; however, this relationship was absent when the statistical analysis was restricted to plasmas with low or very low renin. We also found that, within a rather wide range of values, angiotensin II was more closely correlated with immunoreactive renin than with renin activity. Trypsin activation increased to a similar extent immunoreactive renin and renin activity in plasma of nephric and anephric subjects and, overall, the values of total renin obtained with the two assays were significantly correlated. The results of these comparative determinations indicate that, in general, the measurement of immunoreactive renin represents a valid alternative to that of renin activity and a reliable index of the activity of the renin-angiotensin system. In addition, studies with trypsin activation suggest that even in the anephric state human plasma contains an inactive enzyme convertible into an active form which has immunological properties similar to those of active renin.
 ...
PMID:Comparative measurements of immunoreactive renin, plasma renin activity and angiotensin II in human plasma. 330 96

Trypsin- or collagenase-dispersed renal cortical cells from newborn mice were filtered and cultured. The cultures comprised 25% juxtaglomerular cells as identified by immunocytochemistry. Renin was measured by radioimmunoassay in the culture medium and in the cells at various time intervals. This in vitro system was responsive to isoproterenol, which stimulated renin release in a dose-dependent manner.
 ...
PMID:Cultured juxtaglomerular cells: production and localization of renin. 331 22

In this study we outlined the development of an enzymatic technique to activate plasma inactive renin by trypsin in rat plasma. Using this method, we reported the releasing mechanism of the trypsin-activable inactive renin which has not yet been clarified. Adult male Wistar rats (260-300 g) were kept on regular diet (Na: 260 mg/100g) unless explained and underwent operation under pentobarbital anesthesia (50 mg/kg). Blood samples were obtained from conscious rats through the cannulae, which had been inserted into the left femoral arteries 24h before the experiments. After addition of excessive renin substrate which had been obtained from the 24 h-nephrectomized rat plasma, renin was measured by the commercial RIA-kit (Dainabot). Trypsin (Worthington) treatment (20 mg/ml plasma for 10 min at 4 degrees C) was followed by addition of SBTI (Sigma) (20 mg/ml plasma). This condition maximally increased the rate of angiotensin I generation and did not alter the Km or optimum pH of the renin reaction. In this condition, trypsin reaction was completely inhibited by adding these concentrations of SBTI. The molecular weight of inactive renin (51,000) in the normal rat plasma estimated by Sephadex G-100 column (Pharmacia) was the same as that in the nephrectomized rat plasma. In conclusion, trypsin treatment of plasma (20 mg/ml plasma for 10 min at 4 degrees C) followed by SBTI (20 mg/ml plasma) was justified for trypsin activation of rat plasma. Using this method, we investigated the changes in active and inactive renin after bilateral nephrectomy in the salt-depleted rat. Active renin decreased rapidly after bilateral nephrectomy with a half life of 23.6 +/- 4.0 min. Inactive renin, on the other hand, increased gradually and reached to a plateau 24 h after bilateral nephrectomy, and was kept unchanged during the following 24 h. The infusion of mouse submandibular gland active renin or angiotensin II could not prevent the increase of plasma inactive renin in the nephrectomized rat. These suggest that there may be no feedback mechanisms between plasma inactive and active renin or angiotensin II. Furthermore, we investigated the organ-related sources of plasma inactive renin which markedly increased after total nephrectomy. Simultaneous removals of submandibular glands but not of adrenal glands completely prevented the postnephrectomy increases of plasma inactive renin. But, removals of submandibular glands or adrenal glands alone were followed by no changes in the basal levels of plasma inactive renin.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:[Roles of kidney and submandibular gland in the release of rat plasma inactive renin]. 332 83

A completely inactive renin was isolated from normal human plasma by DEAE-Sepharose column chromatography, 70% ammonium sulfate precipitation and Blue-Sepharose column chromatography. This preparation had a specific activity of 122 ng ANG I/mg protein/h, when activated by trypsin. The inactive renin had an apparent molecular weight of 54,000 daltons as determined by gel filtration on Ultrogel AcA 44. Homogeneous human kidney renin (2.4 ng/100 micrograms of the inactive renin) activated the inactive renin. Trypsin (2 micrograms), highly purified human plasmin (70 micrograms) and homogeneous human plasma kallikrein (130 micrograms) activated the inactive renin by 100%, by 75% and by 17%, respectively. But highly purified human urinary kallikrein (up to 150 micrograms) did not activate the inactive renin at all. Trypsin-activated renin was a little different from natural plasma active renin with respect to molecular and kinetic properties. When the trypsin-activated renin was treated with human urinary kallikrein, its activity was unchanged, but its molecular weight, Km value, Ki value of pepstatin A and pH profile became identical with those of plasma active renin. On the other hand, renin-activated renin had the same kinetic properties of plasma active renin and human kidney renin, but had the same molecular weight (38,000) as human kidney renin that was smaller than natural plasma active renin (43,000).
 ...
PMID:Isolation of inactive renin from human plasma and its activation by proteolytic enzymes. 621 89

Cell suspensions were prepared from rat renal cortical tissue by dispersion with 0.1% collagenase. Unit gravity sedimentation in a 1%-4% Ficoll gradient resulted in a single-cell suspension enriched in juxtaglomerular (JG) cells. Both the cellular renin activity and the amount of renin released into the supernatant increased with time when the suspensions were incubated for 1 hour at 37 degrees C in tissue culture medium. These cells responded to epinephrine and norepinephrine by increasing both synthesis and release of renin. The response was blocked by timolol but not by phenoxybenzamine. Cell suspensions prepared in the same manner but using 0.25% trypsin as the dispersing enzyme neither synthesized nor released renin into the tissue culture medium when similarly incubated. Trypsin-dispersed cells did not respond to catecholamine stimulation. Renin synthesis and release in collagenase-dispersed JG cells were unaltered by changes in Na, K, or Ca ion concentrations. Angiotensin II inhibited release, while saline extracts of clipped kidney from renal hypertensive rats stimulated renin release by these cells.
 ...
PMID:Responses of juxtaglomerular cell suspensions to various stimuli. 626 Jun 44


<< Previous 1 2 3 4 Next >>